Due to the complex maze-like structure of Yoshi Valley, the HUD’s mugshot are reduced to question marks, and the player’s position in the race doesn’t appear at all.

This error would be eventually mostly fixed in Mario Kart 8, nearly 20 years after its debut. Some items like the Red and Blue Shells, occasionally, may miss the character in front of the player.

A fan mod for the game which allowed players to have sex with the character Johnny Silverhand, played by actor Keanu Reeves, was taken down at the request of the game's developer CD Projekt Red as they considered it to be potentially harmful towards those who had lent their likeness.

Despite this, at a promotion for the film The Matrix Awakens, when Reeves was told about it by the Verge, he expressed his pleasure for it.

Exclusive to the Japanese console version of the game are four multiplayer skins based off Yakuza characters Kazuma Kiryu, Shun Akiyama, Ryuji Goda, and Goro Majima.

Inside the Software Excess store in the Galaxy Galleria mall, if you click the Taste icon and then click a small dark rectangle in the top-right corner of the screen, a shopper will come running out from the right, being chased and shot at by a floating Sequel Policeman. This Easter egg went overlooked and undiscovered until 2021.

On the opposite side of the screen however, if you click the Smell icon and click the rectangle on that side of the screen, the narrator would say "Ah! Yeaaa!". Afterwards, if you turn your back on the clerk in the store, he will eventually give you the middle finger and laugh. This secret had been known before.

These Easter eggs were removed from the CD-ROM version of the game, even having gone so far as to remove the pixels of the middle finger from the clerk's sprite. However, they are still present in the EGA 16 and Amiga versions of the game that are based on the original disk version.

On Little States, in "Florida" near the rocket launch pad, there is a hangar that can be entered most easily with the Rocket Belt. When you enter it and then turn around, you will be warped to the hangar in "Seattle".

On Little States, near the rocket launch pad in "Florida", there is a small gas station. If you land any vehicle that needs fuel to run, your fuel tank will be automatically refilled.

On Little States, in "California", you can find a building with a small tunnel at its base that can most easily be accessed using the Rocket Belt. Going through the tunnel, you can find a Nintendo 64 logo on one wall, and coming out the other side will reveal that you have been warped to "New York" on the map.

There is a cave under the castle on Holiday Island that will transform the time from day to night. This can be most easily accessed using the Rocket Belt.

Exclusive to the 3DO version, in the level "The Project", there is a secret exit towards the bottom of the map with a Question Mark caption just before it reading:


Going through the secret exit will boot up a secret Breakout clone, where you control Gex shooting balls up towards isometric cubes. To catch the ball, it must hit Gex's head, or if it is too far away from his head, Gex can shoot his tongue out a short distance to catch it just before it lands. The game's second boss, The Flatulator, also appears in this minigame, and hitting him with the ball will allow Gex to shoot the ball higher, while propellors will occasionally appear to generate more cubes.

This game appears to be another small project that was repurposed into an Easter egg, although there are no known messages or credits that appear during it. It's unknown why this minigame was left out of other versions of the game.

Exclusive to the 3DO version, in the level "The Project", there is a secret exit in the bottom-left corner of the map with a Question Mark caption just before it reading:


Entering this secret exit will boot up a 3D side-scrolling shoot-'em-up level. The game gives you 5 credits and 3 hit points to play through the game. You can pick up remote controls, and after getting enough of them your ship will now have triple shots. For every enemy shot at, the score will change to different quips and numbers at random, including:

•"69 Dude!"
•666 (the Number of the beast)
•90210 (the zip code to Beverly Hills, California and a reference to the 1990 television series "Beverly Hills, 90210")
•"Googleplex" [sic] (Googolplex, the company Google did not exist at the time this demo was made or when Gex was first released)
•"Really high!"
•"Way up there"
•"Astronomical"
•Infinity
•"Score is cool, huh, huh"
•"Are you still counting?"
•"I don't know"
•"I lost count"
•"Who cares!"
•"Who keeps score!"
•"Missed one!"
•"Watch your butt not the score!"
•"Is your controller plugged in"
•"Loser!"
•"You suck!"
•"Sucks to be you!"
•"How bad are you?!"

It was originally a senior college project for Stanford University by programmer Evan Wells, but was repurposed as an Easter egg for this game. On the Game Over screen, the game's credits can be seen:


This Easter egg was first known to have been documented in a pair of grainy YouTube videos from 2007. It's unknown why this minigame was not included in other versions of the game.

The map for the level "The Project" features the hidden message "PHAT CITY".

Present in the game's PC port is an unused electronic remix of the "Radiator Springs Theme" used on the pause menu and main menu from the game Cars. In the final release of that game, only the regular theme is used.

When using the Compost, entering the code "6832202" will cause a hidden message from programmer Steve Conrad to appear:


This message went undiscovered until 2022.

During the third Speed Training level, a metal door on top of a building can be shot at to open it, revealing a hidden group photo of several Neversoft developers behind it. However, it appears that there are at least two different developer photos that can be found behind this door. It's unknown if the appearance of each photo differs by the version of the game being played, or if one is randomly selected when the level is loaded up. This building is located diagonally across from a building with a billboard for Tony Hawk's Pro Skater 2 on it, which was also developed by Neversoft and released the same year as this game. This Easter egg went undiscovered until 2021.

At the starting point of the "Race to the Bugle" level, Ghost Rider can be very briefly seen riding down a building before disappearing. This cameo is an exception to the other Marvel cameos in the game's "What If" mode, as Ghost Rider also appears in the normal level.

After beating the Dog Ending, a pair of hidden cheat codes can be inputted when you continue the game afterwards (if these are inputted on the international versions of the game, make sure that the controller type is set to "2"). These cheat codes went undiscovered until 2018, and their effects were previously believed to only be accessible via hacking:

•Inputting Start/L2/Square/L3 will cause a hidden mini-map to appear in the top-right corner. A series of four raw cheat codes can also be inputted to activate different versions of the map.

•Inputting Left on the D-Pad/Left on the Left Analog Stick/Left on the Right Analog Stick/L2/L1/L3 will cause the Save menu to appear, allowing you to Save anywhere in the game.

In the Dream level, there is a Titanium Bolt that must be obtained by shooting a giant floating crab at a certain point in the level to get warped to a different portion where the Bolt is. It's initially unclear that the player is supposed to shoot the crab specifically due to the hitbox for the warp going beyond the crab, which already floats and disappears out of frame in a loop. However, scoping in on the crab will cause the crosshair to turn red, indicating that it can be hit. Sitting and doing nothing while aiming at the crab for about a minute will cause a hint to appear on the bottom of the screen: "Attack its weak point for massive damage."

This Easter egg went undiscovered until 2022, and is a reference to an infamous gaff during Sony's press conference at E3 2006. During a demonstration of Genji: Days of the Blade, the spokesperson presenting the game claimed that its battles were based on actual battles that took place in ancient Japan, just as a "giant enemy crab" appeared in the demo soon after, with the spokesperson awkwardly commenting on the crab's weak point.

There may also be a second reference to the event when returning to Pokitaru after completing the Dream level, where a lone Scuttle Crab will now spawn in a new spot on the beach.

On the Beach in the northern part of the Western Continent, in a hole in the ruined structures in the area, angling the camera correctly will reveal an out-of-bounds picture of an Asian woman. This person was world builder Fred Selker's girlfriend at the time of the game's development, and its placement at the northern-most/highest area on the world map could be a gesture of affection towards her.

On Tuesdays, Jelfonzo will wear a shirt that has a lip design with a message in the Inklings' language on it. It would take 5 years after the game's release for this message to be translated into English from the Round script variant of the Inklings' language, revealing that it reads "FUCK YOU". The game's art book "The Art of Splatoon 2" features early concept art for the shirt where it was originally titled the "Rounded You Suck Shirt", which translated to English through the Bubble script variant reveals that it does indeed say "YOU SUCK".

In 'The Professor's Lab' level, if the player completed a level and also obtained a chalice there, go to Professor Hamilton Kift's room, then leave his room to touch the chalice on the weapon table. By stepping on the chalice button, the game will crash.