The Nintendo 64, PC, & PlayStation 2 versions of the game contain secret minigames that the player can play.

For the N64 & PC versions, the minigame 'Menezis' is a 2D space shooter where the player controls the letter E firing and dodging projectiles from the letters X, O, & the number 8. This minigame is also included in the Dreamcast version, but was only available as downloadable content at the time of that version's release and can no longer be played without hacks. For the other two versions, it can be unlocked by:

(On N64) holding C-Left while quickly and repeatedly pressing the A+B buttons simultaneously during the credits.
(On PC) typing 'SHOOTEMUP' during the credits roll or waiting after the credits roll.

The PlayStation 2 version contains a different minigame, 'The Schplong', a game that resembles Pong. The player controls a sliding blue bar on the left of the screen and must score to win against the computer player. This can be activated in the level The Iron Mountains during the cutscene where Rayman is riding the hot air balloon. Pressing the Square or Circle button 15 times while the cutscene is playing activates the minigame.