Cheat mode:
Select, A, B on controller two for full fuel and more missiles.
Extra Missles and Fuel
Pause the game with controller 1 and then enter the following code on controller 2: A - B - A - B - Select - A. Then you should get more missiles and fuel.
Super A-10:
Select the A-10 and begin game play. Shoot the 30mm cannon one time and hold X when the phrase "Good Luck" appears. Continue holding the button until the phrase "Super A-10" appears in the lower left corner of the screen.