Troops Meet Wampas
About this scene:
Imperial troops have now entered the base, and our heroes are in retreat. But Threepio makes a quick decision to help throw off the pursuers: he tears the warning sign off the Wampa trap! The unsuspecting troops then enter the unmarked room, unaware of the fate that awaits them there. Afterwards Darth Vader enters to find only the remains of his troops.
This was cut since it was part of the Wampa storyline that ended up being dropped from the film. Originally it gave Threepio the chance for a clever but deadly joke at the Empire's expense. It also explains why he was so far behind the others when they ran into the hangar to board the Milennium Falcon.
Some photos are from the LucasArts Behind The Magic CD ROM, some from other sources. One of the trailers for The Empire Strikes Back actually contains a few seconds of this scene.