Factual error: When the hackers start hacking the traffic cameras there are several shots of vehicles crashing on the computer screen. These shots are supposedly coming from traffic cameras but some contain complex movements such as a crane shot that was obviously done by a real camera.
Continuity mistake: John M is driving to the Eastern electricity station and chatting. The view out of his window shows him driving past the same distant hill at least three times. Also the speed is faster out of the passenger's side than the driver's.
Factual error: After the eastern hub explodes from the gas, and after Mathew's rant, McClane looks out over the city as the power goes out and all the lights begin to shut off. But all the headlights of the cars on the streets also begin to turn off, despite not being connected to the grid.
Continuity mistake: When the one bad guy has got McClane near the start in the alleyway, there is one shot where the bad guy is facing the other way. He goes forwards feet first for one quick shot then goes backwards to hit the dumpster. (00:16:05)
Audio problem: Why does the whole city make a 'whooom' noise when the power turns off? And each block makes exactly the same sound.
Factual error: They crash their BMW, and Doloris comes on in the On-Star system. On-Star has never been available in BMW vehicles, as it is a wholly-owned subsidiary of General Motors. BMW does offer a similar service called BMW Assist, but this was not available in any BMW model at the time of this movie.
Suggested correction: Where did you get OnStar from? It was "RoadAssist", OnStar is not mentioned at any point. Nor do they crash the BMW, Matt whacks it with a bin.
Factual error: When John McClane is driving the semi, an F-35B Lightning II is called in to destroy the semi - the only problem is no variants of the F-35 were in operational service in 2007, and are not expected to be until December of 2015.
Factual error: 0.7% of the electricity generated in West Virginia (as of 2011) is from natural gas. The plant in the movie would have been a peaking unit, only operated during the day. Shutting down a power plant that is not operating would not cause a black out. Further evidence that the unit is not operating is that only three security guards seem to be on the premises. You can not operate a power plant with three security guards.
Factual error: In the scene where McClane jumps off the fighter jet he slides down at 100+ feet of highway concrete but when he reached the bottom his jeans are not torn in any new places. Any fabric rubbed against concrete for any significant distance would be shredded or (if conditions were perfect) at least frayed.
Factual error: This is supposed to be an F-35B, the STOVL version with the additional lift jet. The B model has no internal guns, let alone two firing from the bottom of the air intakes. The only gun it can carry is fitted in a multi-mission pack attached to the belly. (01:54:25)
Deliberate mistake: While McClane drives in the tunnel, Gabriel orders, "Open the gates on the north side entrance." A few shots later the signal light changes from red to green and the north gate opens. The "warning" sign is backwards in this flipped shot. Then, when Gabriel opens the gates at the south entrance, there's a proper shot of the "south" gate opening. The two shots of the "north" and "south" gates opening are the same, but one is reversed. All the dirty smudges on the signs, booths, etc, are identical. (00:41:20 - 00:42:05)
Continuity mistake: While McClane and Farrell are in FBI Police car 279, the windshield's rearview mirror repeatedly vanishes and reappears. (00:38:25)
Continuity mistake: During the traffic jam early in the movie, John and Matt get out of their car and walk away on foot. In the next aerial shot looking down, you see someone stepping out of the very same car they were in. (00:25:27)
Continuity mistake: When driving the semi, McClane collides with the rear of a black BMW, but when the camera shifts to a different angle the collision continues with a cut of the truck hitting a Mercedes from earlier in the scene. (01:48:50 - 01:51:45)
Continuity mistake: When inside the stationary semi-truck the actors are swaying and moving as though the truck is travelling, but it has not yet left the warehouse. (00:50:00)
Continuity mistake: During the plane and semi scene the front of the semi gets shot to pieces. If you look at the windscreen when the semi comes back onto its wheels it's more like a protection cage, then in the next shot it's gone.
Continuity mistake: The wounds on John's right eyebrow and cheekbone change size, disappear, and switch from fresh to dry then back again throughout the film.
Plot hole: Why would Gabriel use a government vehicle at the end of the film that could be easily tracked and give his position away?
Suggested correction: Gabriel using a Government tracked van isn't really a plot hole. The plot hole should actually be how Bowman was able to track it considering Gabriel turned off the satellites. No satellites means no GPS tracking.
Continuity mistake: When John drives over the fire hydrant and the water jet hits the helicopter, the gunman falls out and ends up on the ground between the car and water jet. When John drives off in the long shot his body has disappeared.
Continuity mistake: When McClane is on the phone to Boeman about Thomas Gabriel, the blood on McClane's hand is constantly changing. (01:12:15)
Suggested correction: Not really a mistake seeing the same hill 3 times. Also the speed can alter quite easily. Not a mistake.
Ssiscool ★
Also, the road could be curving slightly, changing the angle of view with the camera change.