Killing Zone Codes -

Fight as the Boss:
Hold L1 + R2 + Circle + Start for approximately five seconds. Then, select single player mode and choose any character.

Ending:
Move to the extreme left side of level 2, then hold Down/Left + R1 + L1, and press Start. The screen will blank and the game will resume to the Boss encounter on the last level.

Audio tracks:
Play tracks 2 through 34 of the game disc in an audio CD player.