Factual error: When the terrorist clears the nearly fuel-exhausted plane to land on the lowered ILS, the terrorist says, "Windsor 114, you are cleared to land on Dulles Runway 29, ILS." Problem is: There is no Runway 29 at Dulles. The closest runway alignment for a 290 degree heading is Runway 30. (00:53:35)
Factual error: When the bad guys 747 is blown up it is about 40 or 50 metres off the ground and travelling at take-off velocity, yet when Holly's plane is landing you can see that the debris field is perfectly circular. Surely the 747s speed and angle of descent would mean the debris field would be elongated? (01:50:30)
Factual error: The chase scene involving the snowmobiles is problematic in that McClane can actually see where he's going. In driving snow, it's often difficult to see, as snow blows in one's eyes. On a speeding snowmobile, in heavy snow and with no eye protection, it would be practically impossible to see anything. (01:31:15)
Factual error: When the 747 explodes, fire is rushing up through the cargo hold. Esperanza - in the cockpit - looks back over his shoulder as if seeing the fire coming. Clearly he can't see the fire - since the view we are seeing is inside the cargo hold and cabin. But why is he then turning his head and looking back against the cockpit wall? And the flash we see on his face - from the explosion - that would not be there until the fire was inside the cockpit. And that would go so fast that he wouldn't have time to scream. (01:50:35)
Factual error: There is absolutely no way the villains could remotely recalibrate the instruments on the plane itself. Even if it would be possible to remotely readjust the ILS glideslope - which it isn't - the pilot would've noticed their approach angle being suspiciously steep on the attitude indicator and the aircraft's radar altimeter would've given a terrain warning. (00:52:44)
Suggested correction: If the pilots are given an incorrect altimeter setting (outside barometric pressure), then yes, they can be fooled as to their altitude.
Factual error: At the time Die Hard 2 was made the only people in the Army that wore black berets were Rangers. If anything an SF (Green beret) team would be responsible for providing aid in that situation. (01:03:15 - 01:28:15)
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)
Suggested correction: The fuel would not light at all, so the tightness of its trail is really unable to be determined in this manner. Assuming jet fuel could light like that, it's possible that only the densest area would be able to catch, which would be the center of the trail... but again, Jet A is pretty hard to catch on fire.
Factual error: There is absolutely no way that Bruce Willis could have stood in the middle of an airport landing zone trying to keep the plane from crashing into the ground. He has no protective ear equipment on - that noise most definitely would have blown his eardrums out and blew him several yards away physically when it flew over him.
Factual error: The first shot of the church is a high up shot which pans down as the van enters the shot. High mountains can be seen in the background. The film is set in Washington D.C. (Note: the film was shot in the Denver area.).
Factual error: There is no Glock 7, and Glocks are produced in Austria, not Germany.
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: 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.
Factual error: A dangerous prisoner like Esperanza would not be flown into a civilian airport. He would be transported to the nearest USAF base, in this case Andrews Air Force base, always assuming that he is being extradited to Washington D.C.
Suggested correction: Runway numbers are based on the magnetic heading of the runway, and since the earth's magnetic field is in constant motion, a runway's magnetic heading can and does change over time. As an example, my local airport's main runway is 30/12, but 10 years ago it was numbered 31/13. Therefore, it is possible that in 1990, what is now runway 30 at Dulles was numbered 29.
Random guesswork isn't a valid correction. A simple google search will show that runway 30 at Dulles has been called that since it was opened in 1962. In 1990 there were 3 runways at Dulles: 1C/19C, 1R/19L, and 12/30.