Continuity mistake: Right before they rob the police car, a Boeing 747 (four engines) is seen in shots of the plane coming into land. When the plane is shown from behind, it is a Boeing 767, with only two engines and fewer main landing gears. (00:30:10)
Other mistake: When Somerset goes back to the man's house alone, he cuts a sticker on the door with his switch-blade to get in. The first error is the sticker is on the inside and it says "Keep Out." The best part about it is the door opens inward. How did they put the sticker on the inside and then exit? (00:20:45)
Continuity mistake: When the two female characters enter the fancy hotel room, they make a point to say they will only be there for a couple of minutes. It is daylight when they go in. The visit is cut short (the one that's supposed to be a few minutes long) because of a gun battle in which one of the women dies and the other escapes. The escaped one gets out through the roof into an evening's sky. There's still light visible, but for a visit that lasts all of 4 minutes, it's far too quick a change. (00:23:00)
Factual error: When McClane and Zeus take the little hatchback from the bank location, they run up the ramp by the Brooklyn Bridge and McClane looks to see the dump trucks aren't on the bridge. Zeus then spots them on FDR Drive and they speed off down the ramp to FDR Drive. The ramp they were on doesn't connect to the ramp they took to give chase. It only heads towards City Hall or over the bridge. They'd have to take the Civic Center ramp, do a u-turn under the Brooklyn Bridge approach then head back up the ramp to FDR Drive.Markyharley
Revealing mistake: When Two Face and Riddler enter Wayne Manor, and knock Alfred down. Alfred, unconscious, pushes the dinner tray aside, so the thugs can carry him into the closet. (01:27:55)
Continuity mistake: Stallone is eating a banana when he is on the computer in the Mariott. He takes a bite and the banana is smaller, then in the next shot it is bigger again.
Other mistake: When Michelle Pfieffer hands out menus for the restaurant in the class, they all read them out loud in English. Then when she takes Raul there, he says he can't read it because it's in French.
Revealing mistake: In one of the final scenes where Stallone is hanging out of the Statue of Liberty, you can see that his "JUSTICE TATTOO" on his upper arm is a fake. You can see at the edge of the tattoo that it is glued on the skin.
Visible crew/equipment: When Neil (De Niro) breaks into Van Zant's apartment and shoots him, watch as Van Zandt flies backward. You can see a wire running up through the bottom of his sweat pants.
Factual error: Near the end of the movie, as the money train is approaching the passenger train, the motorman is communicating on the microphone with dispatch. If you notice, as he is talking, his hand is NOT on the throttle. On the trains in the NYC subway system if the throttle is not depressed the train will stop.
Continuity mistake: In the scene where Max cuts down the bridge and the real scout master dives after Max cuts it down, in the backround in the top left corner you can see the scout master get up, then when the camera goes to the scout master, he gets up again.
Continuity mistake: In the last scene on the roof when Holly Hunter shoots the serial killer, he falls backwards. The gun is in his left hand and the path is next to his left hand. The camera then goes to the rear of Sigourney as she walks toward Holly. Only now the serial killer is on the other side of the path and the left hand holding the gun is no longer next to the path.