Extra Subs In Deep Scan
At the main menu, hold X + Y + Z and select "Deep Scan". Hold these buttons until the game begins.

Faster Subs In Deep Scan
At the main menu, hold X + Y + Z + A + B + C, then select "Deep Scan."

Fight For The Girl
If you beat the game in two player mode, you play against each other to find out who gets to be the girl's new bodyguard. You can play against each other until you run out of credits.

Hardcore Mode
At the main menu, highlight DIE HARD ARCADE, then press and hold X + Y + Z + B. If you did it right you'll have 4 credits and the enemies will be a little harder to defeat.

Helicopter Kick
To do a helocopter kick press A + B + C at the same time