Other mistake: As Dark Helmet says his line "Everybody knows that!", watch the crewman in white to Helmet's right. He starts to cover his crotch a beat too soon.
Other mistake: After the one bad guy crashes into the giant vat of toxic waste, hardly any of the liquid from the container spills out for the first two shots. Then a few cuts later, almost all of it pours from the back of the truck. Judging by the size of the hole it left, more liquid should have been coming out around the truck, not just through it. (01:29:00)
Other mistake: When everyone in the audience and everybody at the betting board see the original unedited version of what really happened at Bakersfield, it shows a soldier hitting Ben with the butt of his weapon from Ben's point of view, which is an impossible camera angle. And as it's the original unedited footage, it won't be something they faked.
Other mistake: The same front shot of Superman flying is used over and over and over again.
Other mistake: When He-Man is fighting against the centurions on the floating disks, he tells the others to get inside a building. As he opens the door to the building, not only does it fall right off the hinges, but his sword also falls right off his back, pulling his cape off with it just as the scene ends. (01:09:20)
Other mistake: During one of the early investigations of the murder in the record store, there is a scene of the FBI agent and the detective in a Porsche driving through an intersection, almost crashing into a yellow car entering the intersection and swerving away to avoid an accident. Later on in the movie, there is another scene of the Porsche going through the same intersection, at a different angle, and almost hitting, again, the same yellow car, at the same position, doing the same manuever to avoid a crash.
Other mistake: When the Predator sees Billy on the log bridge, there is a cold blotch in the middle of Billy's chest. He's not wearing anything that would make such a hole in his heat signature - it should be the same color as the rest of his torso. It doesn't even match up with the cut he made across his chest; the cut starts much higher than the blotch and the blotch is irregularly shaped, not indicating the smooth line of a cut. (01:15:20)
Suggested correction: The cold area is the blood running from his wound. It is cooling down on contract with the air.
Other mistake: When Jack (Martin Short) is injected with the syringe, it's done in his butt cheek, through his pants, just below the waist of his coat. We then see later Margaret looking at photos taken during the scene, one of them shows the syringe injected through Jack's coat into his thigh/butt cheek area.