Floating plasma grenade

In Assault on the Control Room (Level), when you get to the first lift, stand behind the sign that says Press X to Activate. Lift and throw a Plasma Grenade into the center of the lift. The lift will go down, but the grenade will float in front of you. The grenade will harm you, so if you have low health, you will die after it explodes.

Elevator Grenade
A glitch involving grenades can be observed when you throw a plasma grenade into the air while riding an elevator. Instead of exploding, the grenade will keep bouncing until the elevator stops.