Continue:

Press Up + 1 + 2 at the "Game Over" screen, before passing level 8.
REMEMBER: This may only be done twice. To continue until level 17,
press Pause(100) at the title screen before the demonstration screen
appears. Then, start game play and use the previous trick to continue
at any level up to level 17.

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.