Successfully complete the following missions to unlock the corresponding aircraft:

Aircraft Mission
Blue Impulse T-4 Blue Impulse 10
T-2 Blue Impulse 15
F-86F Blue Impulse 20
F-4EJ Sky Mission Attack 1
F-1 Sky Mission Attack 2
F-15DJ Sky Mission Attack 3
Gray F-4EJ Sky Mission Attack 4
F-2 (F-16) Sky Mission Attack 5

At the "Press Start" screen, press L + R. If you entered the code correctly, the phrase "Ok Good" will be spoken. Then "Exhibition" mode, all levels, airplanes, including the dolphin and buggy and more will be unlocked.

Get a dolphin
Successfully complete all nine Sky Mission Attack levels.

Get a buggy
Successfully complete all nine Sky Mission Attack levels.