Revealing mistake: More rounds come out of the Vulcan than are carried by real Harriers.
Audio problem: When the helicopter is following "Carlos the Jackal" and Jamie Lee, it's hovering really closely, yet they never hear it. But you can hear it as they are being taken from the trailer home. (01:00:05)
Other mistake: In a scene where Gib and Harry are getting into their car, if you look very closely you can see a elderly old lady staring into the camera.
Revealing mistake: During the bathroom scene, all the backshots of Arnie taking a pee are of a very obvious stand-in, not the real actor. (00:30:05)
Continuity mistake: During the bridge sequence, the limo drives through an area that is on fire. After emerging from the fire, the passenger side headlights are shown to be blackened from the smoke and heat. Further down the bridge the headlights are shown to be clean and new looking again. (01:56:40)
Audio problem: While on the plane, Helen says 'we are married and we have a child!'. When the shot changes the part 'and we have a child!' does not match her mouth. (01:28:05)
Continuity mistake: After the shootout in the restroom, close to a hundred rounds were fired, all from LOUD guns, yet when Arnold and the terrorist are running through the mall and out the window, people are standing around in the stores, like they never heard a thing. Heck, that AK-47 would even be heard by the people outside on the street. The only one to hear anything is the guy on the toilet. (00:33:30)
Continuity mistake: When Harry is racing the police horse through the park and hotel you see the end of his reins flip up several times. They are regulation length leather reins. Yet when the horse stops and flips him off over the edge of the building, suddenly the reins are about 10 feet long and much thicker. Also, in reality, the reins would probably have snapped or the bridle would have broken had 200 plus pounds hit the end of them at that speed. (00:34:45)
Revealing mistake: In the scene where the harrier shoots a missile and blows up the bridge you can clearly see that it's all miniature, but if you didn't know, you could tell it by the crash barrier that is obviously made of some sort of rubber - it bounces up and down during the explosion (you see it in the frame where the car crashes down on the bridge again). (01:54:10)
Continuity mistake: At the part where Arnold and gang are raiding Simon's caravan and one of them hits Helen on the head with his gun, Arnie punches him on his left cheek, however when he gets up he is holding his right cheek. (01:04:30)
Factual error: In the amount of time it took for Arnold to exit the lake and infiltrate Khaled's party, the mere temperature in the mountainous region would freeze the hole over long before the patrolling guard would come across it. It might not be fully frozen, but enough to be mistaken for being normal to the casual observer.
Factual error: When Arnold's harrier hovers up and a terrorist has to adjust the focus of binoculars, it shows Arnold's face. Being so close, there would be no way binoculars would have a clear view of his face, maybe a blurry eye at best.
Audio problem: When Helen drops the gun she moans something like "Ow! Ew!" but her mouth is closed.
Visible crew/equipment: When Helen tells Harry she slept with the plumber and he kisses her goodbye, watch the reflection on her glasses: When Harry walks out to the right, a crew member standing in front is very noticeable.
Continuity mistake: After Helen drops the MAC-10 down the stairs and it keeps shooting, killing all the bad guys, you see it hit the floor, then the shot changes and it stops on the stairs. (01:46:10)
Continuity mistake: When Helen is about to enter the hotel room she tears her dress' right sleeve off. The strap of her bra is either fallen over her arm or correctly placed over her shoulder, depending on which angle focuses. (01:18:15)
Continuity mistake: In Switzerland, after Harry talks to Juno, there's an underwater angle of the huge crack in the ice through which Harry exited. From the guard's point of view, half a second later, the hole is a mere crack. (00:08:50)
Continuity mistake: When Arnold is talking to the horse after being pulled up on the roof by the reins, his right hand moves from holding the reins considerably far from the horse's mouth to right up next to it between shots. (00:40:35)
Revealing mistake: In the scene where the limo crashes off the bridge after Hellen Tasker has been picked up in the chopper, the camera pans back to show a strut of some sort is falling from below the limo. (01:58:35)
Continuity mistake: When the terrorists burst in on Jamie and Arnie in the hotel room, the positions of Arnie's hands change between shots. Once going from being by his side to one being behind his head instantly. (01:26:25)
Chosen answer: He just exclaims, "Shit!" It's not what he says that makes the henchman let him go, it's that they both realize that if they don't find cover they'll both likely be shot by this random, firing Uzi.