70 lives:
Press C, B, A, Right, Left, C, B, A, Right, Left, C, B, A, Right, Left on controller two at the main menu.

Level select:
Press A, B, C, Left, Right, A, B, C, Left, Right, A, B, C, Left, Right on controller two at the main menu.

All weapons (Japanese version):
Pause game play and press Up(2), Down(2), A, Up(2), Down(2), B, Up(2), Down(2), C.

View hidden endings:
Go underground in the Junkyard stage. Locate the wall before the door with the mounted guns. Climb this wall to find a man that will allow you to fight three Bosses in an arena. Defeat your opponents to view the ending sequences.