Revealing mistake: When all the terrorists are firing their guns at the sky near the end, one of the men is clearly pulling the trigger, and empty cartridge cases are coming out, but there is no muzzle flash like the other guns.
Audio problem: In the scene where Dana's about to fall off the crane, you hear an audio of her screaming "Help me. Help me." But if you look at her face, she's not saying anything. (02:08:15)
Factual error: When Harry's wife is meeting the used car salesman, he says to meet her under the Key Bridge on K street, that would be hard because the Key Bridge is actually over the Potomac river. If that scene was shot in DC it is on K street, under the Whitehyrst freeway. (00:57:30 - 00:58:50)
Continuity mistake: When Harry and Gib are interrogating Harry's wife, she says a line "I don't give a s**t if you understand that or not," and the shot is a close up of her on the heat screen. Notice that her head is tilted down. However, when the shot cuts to the wider angle you can see the heat monitor and her head is instantly at a more upright angle without time for her to move. (01:10:10)
Revealing mistake: In the restroom fight scene, the first villain shot by Arnold randomly shoots his gun as he is dying. Some of the stray bullets hit the urinals. As the camera angle changes to show the bullets hitting the urinal, large flames can be seen as the urinal explodes and falls to pieces. There must have been a small explosive used to make this happen, as the bullet impact wouldn't do this. (00:30:00)
Revealing mistake: Right after the horse motorcycle chase scene, at the next day's debrief, there is a piece of file footage showing the lead terrorist. As per normal practice, there are numbers running in the clip to show where they are in it, however, even when they pause, the numbers continue to run. Most visible when Trilby asks why he's called the 'sand spider'; they pause the tape and yet the play numbers continue to run. (00:41:55)
Continuity mistake: Before Salim Abu Aziz kicks the bathroom stall doors, we can see there are 6 stalls (and Harry is in the 6th one). Salim kicks the first door, but the close up shot shows it's at least the 2nd door since we can see a door to the left of the post with the lock on it. After that he kicks the 2nd and 3rd door. After he kicks the 4th door, Harry crashes out of his stall, but he's 3 stalls over instead of 2.
Revealing mistake: More rounds come out of the Vulcan than are carried by real Harriers.