Continuity mistake: The Stalker, "Shrike," is a persistent hunter, but not terribly quick on his feet. He's sort of a lurching, Frankenstein-like cyborg who is always pursuing Hester Shaw at about walking speed. When Valentine frees Shrike from Sharkmoor prison, miles out to sea, we see Valentine in his airship destroying the prison and we see Shrike's prison cell sink to the sea floor. This cuts to a long distance shot of the prison exploding and sinking in the far background, miles away, as Valentine's airship comes sweeping from the far background into the foreground and out of frame. Almost immediately, Shrike emerges from the surf in the foreground and slowly trudges ashore, implying that he somehow travelled miles across the sea floor just as swiftly as did the airship, in a matter of moments, despite his slow, lumbering gait. (00:47:40)
Continuity mistake: In the first WW2 flashback the protagonist is handing the various items to the Nazi doorman. When he puts down the pen, he is doing it with a left hand in the table close-up, but he picked it with his right, as the left arm is busy holding the coat. (00:02:05)
Continuity mistake: When Rita is running toward the hanger in a scene that mirrors the first film, she is running on a long wood walkway. In the next shot however, she is on the dirt.
Continuity mistake: When Stallone kills the bad guys with skull masks in the corridor of the bar, his motions pointing the pistol don't match the positions of the lemming-like goons he hits. For instance he has the gun all the way to his right for the first one he kills, but the guy is shown with a hole opening in his forehead while he's in the middle of the corridor. (00:29:00)
Continuity mistake: The mayor suffers a bleeding head wound while evacuating City Hall. Several scenes later he is shown with no wound at all. Not even his hair is mussed. (00:40:30 - 00:46:30)
Continuity mistake: When Will comes out of the garage to get Teresa, he has an alien's tentacle attached to him. When he and Teresa go in to the garage, he no longer has the tentacle attached. (00:34:25)