During the title screen, press the pause button exactly 100 times. This will allow you infinite continues until the 18th stage. To continue, hold the D-button in the up position and hit buttons 1 and 2 simultaneously when "game over" appears on the screen.
Easy refueling
Line up with the refueling plane when it appears. Use the D-pad to move across the top of the plane, then press Down + 1 + 2 to refuel.
safe flying
Bank your aircraft as far to the left as possible. Hold the D-pad in this position and you cannot be hit until the 12th stage.