Holy crap, did they really fire that cannon/machine gun when the team came out of the tunnel? Is this on video anywhere?
Yes, they did.
I was right next to one when they were firing...they picked up all the shells when they were done though.
Just to clarify because the misnomer bugs the living crap out of me, that is neither a cannon nor is it mounted on a tank. That is an M2 .50 caliber machine gun with a blank firing adapter, mounted on an up-armored Hummvee.
I will say though, that the combo of this image and the paint splatter truly makes the KSTATEO poster amazing.