Teleporting
In levels where there are objects floating in the air, if you teleport onto them sideways, there is a chance that you will actually teleport inside the object. This is especially true for the green air ships.
Level Generator
Not only can you type in numbers to generate levels, but you can also type in words and it will convert it for you.
Mad Cows
Complete all three shotgun challenges with a 'Gold medal' rank.
Nuclear Bomb
To unlock the Nuclear Bomb, complete all ten deathmatch challenges. If it does not work with all bronzes, try to get silvers and golds.
Super Sheep
To unlock the Super Sheep, complete all Super Sheep challenges with a 'Gold medal' rank.
Banana Bomb
Beat Shotgun Challenge 3.
Bridge Kit
Beat Deathmatch Challenge 10.
Earthquake
Beat Jetpack Challenge 3.
Voice Change
If you type in "team17" on the keyboard in the Quick Fix mission then you will unlock French Lover's voice.