See The President - During gameplay, pres Z, C-Up, and C-Down together, and then launch a homing cluster. the president will jump out as it hits.
Alien Disrupter - On Expert Dificulty, complete Level 7.
View Chopper - At the Choopper Select Screen, highlight a chopper and press L. A screen will appear with the chopper rotating 180 degrees. you can rotate it with the control stick.