Self Destruct
Self Destruct Vic Viper: While flying press UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, X, CIRCLE

Refill Health and Missiles During Combat.
The following code can only be entered once during a mission. Any time during a mission press pause. At the pause screen press UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, L3, R3. You should hear a sound confirming you entered the code in correctly and your health and missiles will be refilled.

Ellen McNichol
Shoot down Albert every time he comes on the screen. This will unlock Ellen for the space missions.

Bonuses
Beat the game to unlock cinemas, bonus planes, and levels.