Factual error: If the Russian cosmonauts need special suits to survive out in space, so should Lacy when she is abducted by Nuclear Man. (00:02:50 - 01:20:20)
Factual error: Austria is famous for its mountains and ski resorts, but certain parts of Austria are quite flat. And the border region between Bratislava and Vienna is VERY flat. No chance to cross the border over a mountain with a ski resort like shown in the movie, unless you take a 600km detour with three more border crossings.
Factual error: The heat from Dutch's body would warm the mud up in a matter of seconds (tested by the Mythbusters). It doesn't even cover all of his skin or his eyes. And the Predator isn't filtering his input for only large heat sources. His normal vision tracks in on a rat hiding just above Dutch.
Factual error: After Robocop stops the criminal from robbing the convenience store by bending his machine gun, the robber tries to run past him, only to get clotheslined by Robocop. The direction the robber flies after getting hit defies all physics. (00:35:15)
Factual error: Ronnie Cox is shot in the heart at point blank range by Brigitte Neilsen, and it looks to me like she's using a large caliber handgun. Keeping track of the action of the film tells us that Cox is sitting up in bed chatting to his friends just three days later. What nonsense. Even if he did survive (unlikely) he'd still be in Post-Op Intensive Care at that stage. He wouldn't be conscious, let alone allowed visitors.
Factual error: When 8-ball gets shot, in the shot which shows the platoon ducking near a wall with Cowboy, Joker and Animal Mother in the front, there are two weapon related errors. Cowboy's M-16 has a nickel (silver colored) firing assembly and Joker's M-16 has an A2 type pistol grip. The A2 types were introduced somewhere around the 80s, and nickel plated assemblies are rarely used (and were invented after Vietnam, too). The nickel assembly is visible at the beginning of the shot, and you can see the A2 grip when Joker is changing magazines (while Cowboy shouts cease fire).
Factual error: In the beginning of the movie just prior to the Bakersfield Massacre, the camera cuts away from Arnold periodically and shows a computer schematic for his location. The very first coordinate that we see is 29º, 43' N by 119º 23' W and is off the coast of Baja California. The last coordinate that we see is 45º 4' N by 119 8' W and is in north-east Oregon. So, in the 35 seconds or so between these scenes, Arnold's helicopter traveled approximately 1050 miles. That's one fast helicopter. This cannot be explained by saying that they just shortened the trip for the movie because in the first computer schematic you see Bakersfield in the distance which is certainly not 1050 miles away. (00:01:35 - 00:02:10)
Factual error: The bad guys attach over a pound of Semtex to the hull of the First Lady's yacht. When it explodes, the blast shatters the windows in a house a mile away, yet apparently doesn't impact the hull. Even as the vessel burns for 5 minutes, there is no discernible list.
Factual error: After his assassination, Giuliano's body is dropped on the street, and another round is fired into him. In the next shot we see a TV reporter saying something, and there are meter-long rivers of blood running across the street. As he was already dead when he was dropped he wouldn't have bled like that. (02:11:45)
Factual error: The Joes chase Cobra into the snowy mountains and attack inside the weird cave. One of the Joe's vehicles splits to a driving section, and Road Block flying up in a little fighter. Road Block is holding a large rifle with both hands, yet the fighter goes up and turns around and begins flying at his control but he never touches a steering wheel or anything. Just his big gun. And he does not speak so no voice commands are given. How is he flying with no hands? (00:19:40)
Factual error: Horace was not holding the shotgun properly - the kickback would have not only made him miss Gillman, but it would have knocked Horace to the ground.
Factual error: When Riggs and Murtaugh are at the indoor shooting range, Riggs shoots a smiley face at long range. Every shot makes Mel Gibson blink and twitch from the bang. No expert marksman would react like that to the gunshot. Nor could his shot placement be so accurate with that reaction.
Factual error: In the farmhouse bedroom scene, the lead character wakes up and a close up shot of the alarm clock shows it is 5AM. Full sunlight is coming through the window, and an exterior shot shows the sun shining on the house and hay bales. The narrative lead-in just explained that it is early October on a farm near Dallas, Texas. The earliest sunrise occurs near Dallas in October is 6:40AM. (00:04:00)