Level select
At the menu with "Continue" and "New Game" options, press X(3), B(3), Y, X. Then, press Black(2), White(2) for the second part of that code. If you entered the code correctly, the phrase "Secret code accepted" will be spoken.

All instant action levels
At the menu with "Continue" and "New Game" options, press Up, Down, Left, Right, L, R, L, R. If you entered the code correctly, the phrase "Secret code accepted" will be spoken.

All planes and missions
At the menu with "Continue" and "New Game" options, press Y(3), X(3), L, R, Black(2), White(2). If you entered the code correctly, the phrase "Secret code accepted" will be spoken.

All environments
At the menu with "Continue" and "New Game" options, press Down, Up(2), Down, Left, Right, L, R, L, R. If you entered the code correctly, the phrase "Secret code accepted" will be spoken.

Invincibility
At the menu with "Continue" and "New Game" options, press Up, Down, Left, Right, Left(2), Right(2), L(2), R(2), White, Black. If you entered the code correctly, the phrase "Secret code accepted" will be spoken. Your aircraft will still take damage, but will not be destroyed.

Infinite ammunition
At the menu with "Continue" and "New Game" options, press Up, Right, Down, Left, Up, Right, Down, Left, L, R. If you entered the code correctly, the phrase "Secret code accepted" will be spoken. When you fire your weapons, the current number of rounds remaining will increase to 9999.

More instant replay views
At the menu with "Continue" and "New Game" options, press Up, Down, Left, Right, R(2), L(2). If you entered the code correctly, the phrase "Secret code accepted" will be spoken.

Big heads
At the menu with "Continue" and "New Game" options, press Right, Up, Left, Down, Right, Up, Left, Down, Right, L, R, L, R. If you entered the code correctly, the phrase "Secret code accepted" will be spoken.

Unknown
At the menu with "Continue" and "New Game" options, press Up, Down, Right, Left, Up, Down, Left, Right, L, R, L, R. If you entered the code correctly, the phrase "Secret code accepted" will be spoken.