Cheat: Invincibility
Collect all the babies in the game. A "Cheat Discovered" message will show up after the intermission and show a baby flying on a jet pack.
Unlockable: Time Slice Camera
Beat the basketball mini-game at the Lower East Quack level to unlock the Time Slice Camera
Unlockable: Multiplayer Level
This is found in New Quack city. Fine the building where you push the statue in front of the camera. There you will find w TV screens with small animations on them. Shoot the one with the BIZZARE company logo on it.
