Continuity mistake: When McClane lights the torches on the runway he is surrounded by rough snow, then the long shot shows a smooth runway in the snow, then when the plane crashes the pilots see the tarmac with no snow, then the outside shot of the plane crashing shows the runway covered with snow again.
Revealing mistake: When the army guy opens the door on the 747 to climb out onto the wing, the outside door handle does not move and looks painted on. When the second guy re-enters the plane and shuts the same door, there is no locking mechanism shown on the sides of the door; it simply pushes open.
Factual error: When McClane lights the fuel with the zippo, the flame trail is all wrong. There appears to be a thin strip of fuel which accelerates away from him. However, we have seen the Fuel spurted out in a wider less controlled manner from a wing tip that has to be at least fifteen feet up, in a wind, which would have sprayed it around further. There is no way it would light in the tight manner shown. (01:45:55)
Continuity mistake: Col. Stewart asks if the 747 is ready and says he wants ground personnel to inspect the plane. Maj. Grant intercedes and tells Stewart to check out his own plane so not to have potential hostages (which, of course was a ploy). When the hanger door is opened, you see ground personnel running back and forth between the door. They are noticeable by their orange vests. (01:33:45 - 01:35:40)
Audio problem: When General Esperanza is trying to land the plane there's a hell of a lot of noise from the wind blasting in through the shattered windscreen. Yet when we see McClane listening in to his radio communication he can be heard completely without a trace of wind noise.
Deliberate mistake: At the very end, John McClane lights the fuel trail which subsequently engulfs the plane. To do this, he tosses a lighter onto the trail which begins six inches from where he lies, having fallen from the wing while pulling the lock off the fuel dumper. Trouble is, the fuel began flooding out at the same time he fell, and the velocity would carry him some distance forward on the ground after he lands (which it visibly does); hence, it is physically impossible for him to be in the position he is in relation to the fuel. (01:50:05)
Plot hole: When McClane gets kicked out of the control tower and is sent down in the elevator with Coleman he quite obviously stops the elevator before saying "Here's a couple of words, F**k off." to Coleman. He then opens the top panel and climbs out WITHOUT restarting the elevator. Almost as soon as he has closed the panel again the elevator has reached the bottom and the cops are asking "Where's the other one?" As it is meant to be a single shot and there is no delay we know Coleman did not start the elevator again herself. (00:38:25)
Factual error: In the tower, Leslie Barnes and a few men are talking about the Annex Skywalk, mentioning that it is a "VHF System." Barnes says the planes are so close it won't matter. VHF, or Very High Frequency, transmits far distances, hence why it is used by airports around the world. He should have said "UHF", which transmits shorter distances, as that would make more sense.manthabeat
Continuity mistake: In the airport lobby, when the two policemen come at the bar they have "snow" all over their clothes. In the next shot they are shown from behind sitting at the bar and Lorenzo's brother has no snow on his jacket. Seconds after Mc Clane comes to talk to them and the cop has snow on his shoulders again.
Factual error: One scene has a shot of an aircraft, in flight, with a red light on the starboard (right) wing and a green light on the port (left) wing. Backwards.
Factual error: You cannot fire 'blanks' and 'live' ammunition from the same weapon without fitting a BFA (blank firing attachment). When a live round is fired, the bullet moving up the barrel seals the barrel. The exploding gas pushes in two directions. One - forcing the bullet out the end and two - pushing the working parts back. The working parts then move forward and pick up a new round. The BFA seals the top of the barrel, as a live round would do. If a live round is fired through a BFA you would be lucky not to blow the barrel.