Invincibility:
Press Start to pause game play, hold L2 + R2 and press Up(2), Down(2), Left(2), Right(2), Square, Triangle, Square, Triangle, then hold Select until the pause screen disappears.

Slow motion:
Begin game play as Max, then hold R2 and press Up(4).

Kurt in boxer shorts:
Hold L2 + R2 and press Square(2), Triangle, Square at the main menu.

Mixed character:
Press Start to pause game play, then hold L2 + R2 and press Up, Down, Right, Left, X, Triangle, Circle, Square, Square + Start to play as a character that is part Kurt, Max, and Doctor Hawkins.

Panning camera view:
Press Start to pause game play, then hold L2 + R2 and press Circle, X, Circle, X.

Crazy camera view:
Press Start to pause game play, then hold L2 + R2 and press X, Circle, X, Circle.

Fixed camera view:
Press Start to pause game play, then hold L2 + R2 and press Circle, X, Circle, Triangle.

Fart sounds from Doctor Hawkins:
Begin game play as Doctor Hawkins, then press L2 + R2 + Left + X.