Continuity mistake: McClane rips the airbag out and tosses it on the road. When they drive away, the airbag has gone. (00:57:30)
Visible crew/equipment: Just as McClane jumps down the cab of the semi, there is a quick shot where the camera shadow is visible on the semi. (01:43:05)
Continuity mistake: When McClane and Rand fight in Woodlawn, Rand falls down through two sets of blades rotating at high speed. Once he goes through them, the blades appear to be slowing, but at the next shot, not one second later, the blades are rotating at full speed again. (01:41:55)
Factual error: Where the film shows the power going out on the Eastern seaboard of the US, it shows the lights going out at an airport. At the airport the tail of an aircraft with the Air New Zealand logo on it is seen. Air New Zealand does not fly to any airport on the Eastern seaboard of the USA.
Deliberate mistake: When John crashes the car against the elevator room, the cables he and the woman hold on to are clean, when they should be greasy - thus allowing for them to hold safely.
Revealing mistake: Airbags are made out of a super strong fabric material with heavy weaving. There's no way McClane would be able to tear it. You can see the texture difference between McClane's fake airbag and the real passenger side airbag.
Suggested correction: Incorrect, the driver's airbag is designed in such a way it can be ripped out. This is a safety feature to be used in a life or death situation if the car is still driveable. For instance, if someone rams you off the road and the airbag deploys, you can rip it off and continue driving to try and escape the assailant.
Plot hole: When in the tunnel, McClane gets back into the cop car and leaves Farrell, he drives very quickly. After the helicopter blows up, it is only a few seconds before Farrell finds McClane. Even running at his top speed, Farrell could not have reached McClane's position so quickly. (00:42:00)
Continuity mistake: When McClane is driving the police down the ramp to the tunnel so he can elude the helicopter, the car's windshield doesn't have any bullet holes or cracks in it, even though it did just a few seconds earlier. (00:37:55)
Continuity mistake: In the next-to-last shot of the movie you can see giant letters SOU on the warehouse behind Bruce Willis sitting in the ambulance. In the final wide-out shot of the movie the same warehouse has no lettering.
Audio problem: As McClane attempts to escape from the car in the lift shaft, a henchman shoots at him. As McClane hides between the seats, he cries, "Motherf**ker!" However, McClane's lips aren't moving. ('Unrated'/'Ultimate Action Edition' version only).
Continuity mistake: In the scene where the semi driven by McClane is chased by the F35, the semi hits multiple vehicles causing it to damage. The driver side headlights are smashed and the bumber and fender are almost scraping the ground. In the next shot, headlights, bumber and fender are fine.
Factual error: The hazmat van is shown to be a Mercedes Benz. The problem is that in 2007, when the movie was shot, this was sold by and as a Dodge. It was only sold as a Mercedes from 2010 onwards. Presumably it was rebadged as part of a product placement deal. (01:48:55 - 01:51:50)
Continuity mistake: While McClane is taking control of the Freight liner during the final chase, he jumps onto the driver's steps, and we see the driver's side window is closed, he shoots the driver and whips the door open, and the window is now open. He climbs into the truck and slams the door, and the window is once again closed. There was obviously no time for the window to be opened and closed during the fight.
Continuity mistake: At the very end when McClane is talking to Farrell, he has three steri-strips over his left eye, but when he goes back to his daughter he only has two.
Factual error: The cyber attack takes place on the 4th of July which is a national holiday, the stock market is closed and so are government offices, no politicians are meeting at the Capitol.
Factual error: There are several mistakes after McClane steals the 18 wheeler that give away the highway scenes were shot in California instead of Maryland. There are palm trees visible at one point outside the window. There are highway signs that indicate Route 118 and Highway 110, both in California. The scene with the fighter jet is supposed to be on I-695, the Baltimore Beltway, but that road is single-level, not multi-level as the movie shows. A green bridge is visible after part of the highway collapses but there is no bridge that looks anything like that on I-695.
Factual error: Near the end of the film there is a shot of the FBI helicopters turning. Mountains are visible in the background. This film is supposed to take place on the east coast. There are no mountains that tall on the east coast.
Continuity mistake: At the end when McClane shoots through himself to kill the bad guy, it's though his right shoulder into the bad guy's right shoulder. The next shot of the dead bad guy has the wound in his left shoulder.
Plot hole: After McClane, agent Johnson, and Ferrell leave in the police car, Agent Johnson radios another agent to have DC police clear a path for them. Then on Gabriel's screen it says they have a voice match to Farrell. The problem is Farrell never said a word, so how would they have a voice match to him? Without the voice match they never should have found them.
Suggested correction: The agent says "Ferrell" over the radio which in turn gets picked up as a name match on Gabriel's screen as they were scanning for anyone using that key word. Not Ferrell's actual voice but anyone mentioning his name over the radio.
If it was just looking for anyone saying the word Farrell it would have been a "voice" match. A voice match implies but they got a match to Farrell's voice.
In this context it is a match on the name "Farrell" that was spoken, hence it is a "voice match." It's clunky but still works grammatically.
Factual error: When McClane and Ferrell are stuck in the intersection with the helicopter shooting them, the bad guys pull up the scene from a camera on the building. Clearly the camera is stationary, so why is the shot on the computer moving?
