Quoting: Anticheese
How many rocket launchers do you see getting crushed in doors?
Sure, they wouldn't get crushed, but the door would remain open in that case.
Quoting: sn0rb
You can close a door on yourself, too. =p
Yeah i just noticed that too 0.o
Enemies still see you and shoot at you, but you can't get hit when you stand on a closed door. Pretty abusive bug i'd say.