On the main menu, enter circle, X, right, left, right, left, down, down, up, up.

Versus Mode:
First, you need to sucessfully finish the game this can be done on any difficulty setting, this will unlock versus mode with most stages and five frames. To be able to unlock the last 2 frames and stages you again need to sucessfully finish on any difficulty setting to times to unlock these.

Alternating Music:
As above again sucessfully finish the game on any difficulty setting but must achieve an 'A' Rank on all the 5 rescue missions to be able to hear a different ending tune during the end credits.

AT THE 'PRESS START' SCREEN PRESS -
O, X, RIGHT, LEFT, RIGHT, LEFT, DOWN, DOWN, UP, UP.

Disco Mode - Press Up Down(2) Triangle X left right Square on the title screen. All enemies are now disco balls. beat the game in this mode and you will get a suprise