Pearl Harbor: Zero Hour

Hidden bonuses:
Click on the airplane shadow on the right side of the mission selection screen to unlock another level and three additional airplanes including the Raptor and UFO.

Note: The airplane shadow does not appear until level 10 is completed.
James White.

In almost all levels are special individual standing palm trees. Shoot those trees down to get 500 skill level points. A message stating "Enemy <name>'s Favorite Tree, +500" will appear. Note: Most levels have more than one of the those special individually standing palm trees.

Hint: UFO attack:
Use the UFO to crash into some U.S. buildings. They will become distorted and you get points as if you were the enemy.
BeastyV.