# All games

At the game selection screen, press Up, Down, Up, Down, L1, L2, L1, L2 to unlock all games.
# Rainbow effect

While in the Rainbow play room, press Circle to change how the effect works. It is somewhat inversed and is interesting to see.
# Easy wins

Put your entire hand over the camera's lens.
# Easy win in Wishi-Washi

Walk left and right in front of the camera in hard mode to wash a lot of windows and get a very high score.
# Extra tracks in Boogie Down

Get a high score on Boogie Down to unlock more tracks.
# Hit enemies easier in Kung Foo

Get some kind of stick or pole and hit the enemies with that. Do not keep swinging, but see what you are actually hitting.
# See infrared from remote control

Take a remote control from a television or other device use it on the Eye Toy. You will see the infrared light that is normally invisible to the naked eye.
# Wrong dialog

When playing the Boxing game on any difficulty setting in the Japanese version of the game, either get a good score or knock out the robot. After the match, the trainer who helps you will say "You'll make that robot...", but the on-screen subtitles clearly read "That'll make that robot..."