That Ended Up Working Out Nicely
After taking control of the enemy transport in Act 2-2, do not let a single enemy escape.
Fisher is the Other Sam
Proceed on the monorail in Act 3-4 without being spotted by the enemy troops or searchlights.
Ignore the elevator start order in Act 4-1. Instead, hold position and destroy all reinforcements.
The Best of All Possible Worlds
Find and fire upon all of the Pangloss statues hidden on the colony.