To enable these cheats first you need to hold down R1 + Circle while the game is loading or continuing a game. Then when the flying CDs appear enter these codes:

Tons of Credits:
At the special CD loading menu, quickly press Down, Circle, Triangle, Triangle, Triangle, Circle, Triangle, Circle, Triangle, then press Circle and Triangle simultaneously twice and hold both buttons down after the second press. You'll see a Pooka character from Dig Dug appear in the corner of the screen to confirm the code. Now start the game and you have instantly earned an incredible 999,999,000 credits.

Colorless wingmen:
Hold down R1 and hit Start 10 times....continue holding the Start button after the 10th press.

Displays the original paint jobs of the planes :
Up, Left, Down, Right, Up, Left, Down, Right, R1

Mini-game:
Up, Left, Down, Right. You can play for about 6 seconds and if you get a score higher than 4.7 you receive a new wingman.