Continuity mistake: In one scene we see the map of the power grid of Eastern Sector shutting down. All sectors are red. A few scenes later we are in Warlock's basement. He has the same map on one of his screens, but there some sectors are red and some are green.
Continuity mistake: When John and Matt are in the patrol cars and Gabriel has them rerouted to a blocked road, there are no cars on the road besides the patrol cars, but throughout the scene when the camera cuts you can see traffic moving smoothly along with them.
Continuity mistake: During the final chase, the right front tire of the Freight liner is flat at one point after hitting a number of parked vehicles. The next shot showing the front of the truck shows the tire is fine.
Continuity mistake: The hacker slaps McClane's daughter moving her head to the right, hair messy around her face. The immediate angle from the hacker's point of view shows her head tilted to the opposite direction, with her hair perfectly brushed.
Factual error: The F-35 JSF is shown having 2 guns coming from the side of the intakes and can fire for a long time. The M61A2 Vulcan Cannon on the JSF is above the left air intake and can only fire for 4.8 seconds before it runs out of ammo.
Audio problem: When Gabriel is starting to move out with the large truck, you hear the sounds from the truck tires but the tires aren't moving.
Continuity mistake: In the semi chase scene when Bruce takes control of the truck he initially shoots twice through the door and you see two 'bullet holes'. When the cut to the cab the driver is shot 5 more times. After Bruce throws out the driver and closes the door you only see the two original 'bullet holes'. There should be about seven of them.
Other mistake: When Gabriel looks at McClane's police record it mentions McClane receiving a commendation for the Chicago airport incident in 1990. That incident happened at Dulles Airport in Washington D.C., not Chicago.
Plot hole: When Lucy is stuck in the elevator, and they re-activate the elevator and turn all the lights on, Lucy should have been able to push the buttons and get to the floor. She did not have to wait for someone to rescue her.
Factual error: In the scene with the traffic jam in DC the traffic lights are green in all directions. Traffic lights are built with a mechanical stop that prevents this from happening.
Factual error: At the power plant the natural gas is shown burning inside the pipeline. Natural gas pipelines are void of oxygen. No matter what the temperature or pressure in the pipeline the gas would not combust.
Factual error: McClane is able to stand on a jet with its engines on but it would be way too hot to do that.
Continuity mistake: As McClane is powering up the helicopter to fly to Warlock, the rotors are already up at full speed. The next cut shows the helicopter in full from outside with the rotors turning much too slow compared to the previous and following scene.
Continuity mistake: When being escorted by the FBI near the beginning, they are in an FBI car which is plain white. They then get shot at by the helicopter and are seen speeding away in the FBI car. A few shots later this car becomes a normal police squad car.
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.
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.
