Easter egg

An Easter egg is a minor secret in a game that is hidden by the developers and is usually not associated with the gameplay.

Easter eggs in Super Mario games

Donkey Kong franchise

Donkey Kong

• In the Atari 800 version, losing Mario's last life because of a fall, while in a point range of 33,000-33,900 (thus ensuring a new high score), and highlighting a Fireball in the difficulty selection will cause the initials of the port's developer, Landon Dyer, to appear in the title screen while the player waits for the attract mode to start up again.

Donkey Kong Country (Game Boy Color)

• The "Rareware Cow" can be found in the level Slipslide Ride.

Donkey Kong Country Returns

• In Button Bash, there are references to Billy Mitchell (a statue with his tie) and to the Three Wise Monkeys.
• In Foggy Fumes, the level 25m from the original Donkey Kong arcade game, Mr. Game & Watch, and a crane resembling Crocomire's skull from Super Metroid can be seen in the background.
• In the options screen, a coral reef is shaped like the Rareware symbol.
• In Wonky Waterway, the last part shows an 8-bit Donkey Kong statue holding a Wii Remote.
• During Donkey Kong's idle animation, he pulls out a Nintendo DS and can be heard playing Donkey Kong.

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  Mr. Game & Watch in Foggy Fumes

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  The 8-bit Donkey Kong statue holding a Wii Remote

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  Donkey Kong playing with a Nintendo DS

Donkey Kong Country: Tropical Freeze

• As Retro Studios had previously developed the Metroid Prime series, two Metroid Easter eggs can be found in the game:
  • Samus Aran' Gunship can be found in the background in Busted Bayou.
  • A Metroid can be found in the background in Amiss Abyss, if the player passes the first signpost and giant illuminating statue, reaches the end of the trench and heads back towards the statue through the anemone. (The player must have more than one hit point to do this.)
• During Donkey Kong's idle animations he pulls out a Nintendo 3DS and can be heard playing one of several games, including Mario Kart 7, Donkey Kong Country Returns 3D, Animal Crossing: New Leaf, and Super Mario 3D Land.
  • In the Nintendo Switch port, Donkey Kong's idle animations have him pull out a Nintendo Switch in Handheld Mode, playing the Switch port itself.

Super Mario RPG: Legend of the Seven Stars

• In Super Mario RPG: Legend of the Seven Stars, there is a room in Booster Tower which features two curtains and a pillar, which will transform Mario into his Super Mario Bros. appearance. Mario will revert back to normal after leaving the room or after a few minutes pass. This can only be done once per game.

Paper Mario series

Paper Mario

• There is a room inside Boo's Mansion containing a vase that will transform Mario when jumps inside into 8-bit Mario and Mario's theme will play. Mario will revert to back to his standard form if he leaves the room or jumps back into the vase. Unlike Super Mario RPG in which the 8-bit trick can only be performed once, in Paper Mario it can be performed repeatedly.
  • Similarly, Mario's theme can be heard if the player waits on the chapter screen long enough.

Paper Mario: The Thousand-Year Door

• During Princess Peach's Interlude after Chapter 5, TEC asks Peach to drink an invisibility potion in order to secretly enter Grodus' room and upload important data on a disk into the room's computer. When this happens, the computer screen shows the Famicom Disk System boot-up sequence which is then shortly followed up by an animation and some music from an unknown game.
• Similar to the first Paper Mario, in the X-Naut Fortress there is a room that, when entered from above into a changing room, makes both Mario and his partner an 8-bit sprite. This wears off after leaving the room or after a period of time. This can be done repeatedly.

Paper Mario: Color Splash

• When using the Megaphone Card, if the player shouts into the microphone on the Wii U GamePad to increase the Thing’s power, it would be heard in the game.

Mario & Luigi series

Mario & Luigi: Superstar Saga

• If the game is played on a Game Boy Player and a second controller is plugged into the GameCube, it functions similarly to a makeshift co-op mode.

Mario Kart series

Mario Kart: Double Dash!!

• Luigi's NEW Mansion (specifically the Rank A mansion) from the ending of Luigi's Mansion can be seen in the background of Luigi Circuit.
• Several courses can be seen in the background of other courses.
  • The top of DK Mountain can be seen from both Baby Park and Dino Dino Jungle.
  • Daisy Cruiser can be seen out in the water from both Peach Beach and Yoshi Circuit.
  • Both Mushroom City and Mario Circuit can be seen from Mushroom Bridge. In addition, Mushroom Bridge can be seen from Mushroom City.
  • Mushroom City can be seen from Rainbow Road, as well as far out in the distance from Wario Colosseum.

Mario Kart DS

• Just like in Mario Kart: Double Dash!!, Luigi's NEW Mansion can be seen in the background of GCN Luigi Circuit.

Mario Kart Wii

• Just like in Mario Kart: Double Dash!!, Daisy Cruiser can be seen in the background of GCN Peach Beach and GCN Daisy Circuit, despite Daisy Cruiser itself not appearing as a track in this game.
• The planet that Rainbow Road takes place over is the real Earth, with the track taking place over eastern Canada.

Mario Kart 8 / Mario Kart 8 Deluxe

• In Water Park, if the player sits in the middle of the merry-go-round ride, the merry-go-round theme from Super Mario 64 starts playing.
• Off in the distance in Sunshine Airport, a koopa-shaped rock can be seen, similar to the one found in N64 Koopa Troopa Beach.
• If the player sits still for long enough in N64 Royal Raceway, the Toads will start to activate the burners on their hot air balloons.
• It is implied that Toad Harbor, N64 Rainbow Road, and Super Bell Subway all take place in and around the same city. The city map in Super Bell Subway appears to be the same as the city in N64 Rainbow Road, and the same Peach statue can be seen in both N64 Rainbow Road and Toad Harbor.
• Similar to Mario Kart Wii, Rainbow Road takes place over the real Earth, this time over the Mediterranean Sea.
• Daisy Cruiser can be seen out in the water in GCN Yoshi Circuit.
• One of the structures in the city in N64 Toad's Turnpike bears a resemblance to the Tokyo Skytree, the tallest tower in the world.

Super Mario series

Super Mario Bros. 3

• If any airship level (except in Dark Land) is beaten as Frog, Tanooki, or Hammer Mario, the kings react with special dialogue.

Super Mario 64

• When jumping in shallow water, a fish will rarely jump out alongside Mario.
• At the end of Bowser in the Sky, images of 8-bit Bowser and Mario from Super Mario Bros. can be seen on the pillars.
• If Mario performs a dive while next to the Baby Penguin, the penguin will also perform its own dive.

Super Mario Sunshine

Isle Delfino

• When FLUDD scans Mario at the beginning of the game, clips of Mario fighting bosses from Super Mario Bros., Super Mario World, and Super Mario 64 can be seen in the bottom left corner of the screen.
• In Noki Bay's third mission, Red Coins in a Bottle, the building at the very bottom houses a book behind an unmovable door.
• The island of Isle Delfino itself is shaped like a dolphin, an allusion to the code name of the GameCube while it was in development. Delfino also means "dolphin" in Italian.
  • In addition, dolphin shapes appear throughout the game, as designs on walls, statues, and graffiti.
• Since the entirety of the game takes place on or near Isle Delfino, most stages can be seen in the background of other stages:
  • Delfino Airstrip is visible from Delfino Plaza.
  • Delfino Plaza is visible from Delfino Airstrip, Bianco Hills, Ricco Harbor, Gelato Beach, and Pinna Park.
  • Bianco Hills is visible from Delfino Plaza, Ricco Harbor, Gelato Beach, Pinna Park, and Sirena Beach.
  • Ricco Harbor is visible from Delfino Plaza, Bianco Hills, Gelato Beach, and Pinna Park.
  • Gelato Beach is visible from Ricco Harbor, Pinna Park, and Pianta Village.
  • Pinna Park is visible from Delfino Plaza, Bianco Hills, Ricco Harbor, Gelato Beach, and Sirena Beach.
  • Sirena Beach is visible from Ricco Harbor, Gelato Beach, and Pinna Park.
  • Noki Bay is visible from Pianta Village.
  • Pianta Village is visible from Ricco Harbor and Pinna Park.
  • Corona Mountain is visible from all other stages.
• Much of Sirena Beach is shaped like a GameCube controller, which is visible from the upper floors of Hotel Delfino.

Super Mario Galaxy

The hidden train.

• In the Rolling Gizmo Galaxy, if Mario or Luigi skips the Star Ball and jumps up the blocks and raised bridge that the player would normally smash with the ball, a Rupee from The Legend of Zelda series made out of blue Star Bits can be seen if the player looks down.
• In the Toy Time Galaxy, on the planet with the first Spring Mushroom, if the player goes on the edge of the block below the warp pipe, they will notice that there is an opening. If they then go to first person view mode once in there, they will see a toy train.
• The Planet Rocket from Space Junk Galaxy can also be seen in the background of certain missions in Ghostly Galaxy.
• If the player gets to the end of Purple Coins on the Battlerock or Battlestation's Purple Coins without collecting any Purple Coins, the Gearmo at the bottom will have unique dialogue.
• When the player collects 9999 Star Bits, all of the coconuts will turn into watermelons.
• If Mario rescues Luigi in a mission but then falls into a black hole before collecting the Power Star, Luigi will ask Mario if he is okay the next time he is spoken to.

New Super Mario Bros. Wii

• If, after having entered a level in multiplayer, a player loses all their lives and cannot respawn, they can play various sound effects by pressing the jump and dash buttons and switch between different sound effects by using the directional controls. These sound effects include the sound of a clown horn, clapping, a cuíca, a bass drum, a snare drum, and a bell.

Super Mario Galaxy 2

• Three alien-like figures appear in the background of Shiverburn Galaxy watching Mario/Luigi (they also appear in the Pull Star planet of Grandmaster Galaxy).
• On the Starting Planet of Sky Station Galaxy, the sign in front of the door is usually signed "Yoshi". However, during the Prankster Comet mission, it is signed "Yoshi the space dragon".
• During the fight with King Lakitu, running out of the arena and back to the checkpoint will make him fall asleep.
• If the player loses a life during the Whomp King battle, on the next attempt, the Whomp King will cut his speech short and say, "Arrrgh! I'm tired of this speech!"
• If the player slides down Tall Trunk's Purple Coin Slide without collecting any Purple Coins, the Gearmo at the bottom will notice and ask whether the player did it on purpose.
• Like in Super Mario Galaxy, all of the coconuts will turn into watermelons once the player has collected 9999 Star Bits.
• If the player has exactly 777, 7777, or 9999 total Star Bits, Lubba will have unique dialogue, mentioning how lucky the player is or wondering what it takes to get that many Star Bits.

• 

  The alien-like figures

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  The sign signed "Yoshi the space dragon"

Super Mario 3D Land

• Using the binoculars in certain levels will allow the player to spot a passing UFO in the sky.
• In World 4-4, when the player reaches the end of the level and stands at the gates to the right for a number of seconds, a ghostly figure will appear slowly out of the background. Once enough time passes, it will open its mouth wide and flash, while fading out at the same time. The figure can also be found at the beginning of World 8-4 and Special 6-5 if the player stands by the window long enough.
• In the letter sent by Princess Peach after completing World 4, shaking the 3DS enough will cause a Goomba and Luigi to appear jumping in the background.

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  The UFO in World 1-3

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  The ghostly figure in World 4-4

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  The ghostly figure in World 8-4

New Super Luigi U

The hidden Luigi sighting in Spinning Sandstones.

• In every level in the game, there is a hidden sighting of Luigi. Every level has one hidden Luigi except for Flying Squirrel Ovation, which has two.

Super Mario 3D World

• Most of the levels and some of the maps feature an 8-bit Luigi, similar to New Super Luigi U, though they use the original Super Mario Bros. sprite instead of the modernized sprite.
• In The Great Tower of Bowser Land, when interacting with the smoldering remains of Bowser's Muscle Car, sound effects from Super Mario World will play on occasion.
• In the credit sequence when it fades out to the sky, the Comet Observatory is visible.

Super Mario Maker

• If the player places a pair of door objects and taps on one, knocking can be heard on the other side of the door. If the player taps enough times, Weird Mario will appear out of the door in a random powered-up state depending on the game style (for example, he can be Raccoon Mario, Tanooki Mario, Statue Mario, Frog Mario, or Hammer Mario when this is done in the Super Mario Bros. 3 style). This returns in Super Mario Maker 2.
• In the Super Mario Bros. style, if the fortress behind the Goal Pole has a locked door on its entrance and the player has at least one key, when they touch the flagpole and enter the fortress, the door will open as if the player unlocked it in-game.
  • Similarly, the same thing happens with a normal Warp Door or an active P Warp Door if it is placed in front of the entrance.
• If 10 Mario Challenge or 100 Mario Challenge is cleared in the Super Mario Bros. style with the Bowser, Toad, or Princess Peach Mystery Mushroom costume, the real Toad or Princess Peach reacts with special dialogue.
• On very rare occasions, when Mario falls into a pit, the death jingle is preceded by one of the eight longer sound clips (e.g. Mario falling down a very long pit).
• If the player shakes a Spike Trap in the New Super Mario Bros. U ground theme, a train whistle can be heard.
• Sometimes, when touching a Checkpoint Flag, several birds fly from the flag; in underwater levels, fishes appear from the flag instead.
• In Super Mario Bros. 3-style ground levels, should Mario keep crouching on a white Semisolid Platform for approximately five seconds, he will do a short little hop along with a sound effect, as a reference to the mechanic from the original game where Mario could drop behind the background using white Semisolid Platforms (which is required to obtain the first Magic Whistle in World 1-3). This also works in Super Mario Maker 2.
• Holding , , and while a course loads will activate a CRT screen filter, similarly to the Big Mushroom; unlike the Big Mushroom, this is functional in all four game styles.
• When editing a level, attempting to use Mr. Eraser on or place a Burner in front of Mario causes him to crouch in fear. This also works in Super Mario Maker 2.
  • Similarly, some enemies have unique reactions when the player grabs them; for example, Wigglers and Chain Chomps extend their segments and chains, Boos hide their faces as if they were looked at, Hammer Bros. occasionally throw hammers, and Bowser in the Super Mario Bros. 3 and New Super Mario Bros. U game styles becomes panicked as if he is defeated.

Super Mario Odyssey

• If there are no controller inputs for a long time, a small bird will sleep on Mario's nose. The type of bird changes depending on what kingdom Mario is in.
  • Similarly, if Mario sleeps in a place where the dog appears, it will sleep next to him.
• The brochure held by Hint Toad and in the Odyssey shows a map of Bob-omb Battlefield from Super Mario 64.
• Bowser's reaction quote to Mario changes according to the costume Mario wears. As of the version 1.2.0 update, Luigi also gives a reaction quote.
• Like Super Mario 3D World, 8-bit character sprites can be found in several levels.

Super Smash Bros. Brawl

• In Super Smash Bros. Brawl, a picture of a cat appears in a cabin in Pokémon Stadium 2 when the stage is Ice-themed.
  • This cameo returns in Super Smash Bros. for Wii U, but with a different cat picture.

Captain Toad: Treasure Tracker

• If the player waits on the game's title screen for long enough, they will be taken to one of two hidden levels. Both levels show off optical illusion of some kind, and the Toad Brigade is also present.
• Like Super Mario 3D World, 8-bit sprites of Luigi can be found in most levels of the game, including in the aforementioned title screen levels.
• Additionally, the levels Spinwheel Library, Double Cherry Spires, and Beep Block Sky Plaza have hidden 8-bit sprites of Rosalina.
• In several ghost-themed levels, there are events that happen if the player waits for a while in the level.
  • In Bizarre Doors of Boo Mansion, ghostly handprints appear on the back wall of the mansion.
  • In Sinister Street Signs, a small thin ghost will fly out of a grate in the bottom of one of the towers.
  • In Fright Train Flight, a laughing ghost will appear under the train tracks in front of the train.
  • In Ghost Gallery Gambit, if the player does not walk towards the star to start the poison rising, several spooky sounds will join the ambient music after a while.
• By turning the camera around at the beginning of any Coins Galore stage, the Starshroom can be seen in the distance.

Wario franchise

Wario World

• If the player remains on the pause screen for 50 minutes, Wario apologizes for his taunting and stops; this applies every time the player pauses.

WarioWare: D.I.Y.

• If a record, comic, or microgame is named "Mario Paint," a remix of the "Creative Exercise" song from Mario Paint plays while it is created.
  • Similarly, when stamps are selected, a remix of the "Monkeys" song from the same game plays.
  • This also applies to stamp editing, where a remix of the "Mysterious" song also plays.