 Part of a scene that involves Parker, Ripley and Lambert trying to flush the   alien out of the air lock.  As they are about to succeed, an alarm is   triggered and the alien rushes out of the airlock (getting its tail caught   in the closing door, and spilling acid that causes a hull breach).  Parker   falls unconciously to the floor, Ripley does the same and Lambert and Ash   come to their rescue.  Ripley vocalizes her suspicions about Ash by accusing   him of setting the alarm off. 