Other mistake: The Hitcher reverses his pick-up truck out of the gas station after he drops the lighted match. His wheels, wheel arches and perhaps the underside of the truck would have been soaked in petrol as he drove over the gushing pumps. So as he was burning rubber during this manoeuvre - this would have ignited the petrol on his truck.
Other mistake: In the scene where Stallone is at the shooting range, after he leaves the morgue, when he pulls out his gun, you can see a target's reflection in a glass pane in front of Stallone. He points the gun at the target and shoots, but the glass is in the way.
Suggested correction: There's no glass in front of him. The glass you're referring to is part of the partitions on the sides. You can see the first one when he and Gonzales walk in and Gonzales is asking what they can do. The reflection is in the 2nd partition that is to Cobra's left. The camera angle just makes it look like it could be in front of him.
Other mistake: After finding that he has run over a dummy and not a live person, the officer doesn't resume the car chase even though Roland's panel truck is shown driving only about one block ahead of him with no traffic in between. For those of you who don't know, panel trucks have the get-up-and-go of an arthritic turtle. (01:21:00)
Other mistake: The computer 'keyboard' in the control room is in fact a Commodore 64 Home Computer.
Other mistake: The subtitles of the international version translate a few things completely wrong, including, when the body of the warden is found, "There were three men!" instead of "It happened at half past three." (00:04:25)
Other mistake: Harry Shannon tells Mark Kaminsky that the alias he is giving him is that of Joseph P Brenner which to a guy with a long rap sheet. Paulo Rocca later asks Joey, "how the hell is it you never did any time?" (00:20:56 - 00:39:53)