Factual error: The sound of an airbag detonating is very loud, even more so with two detonating at the same time, quite a bit louder than what was depicted onscreen.

Audio problem: Just as McClane and Farrell are about to leave the Eastern Power Hub, Farrell goes on a long rant and his mouth does not match the words he is saying.

Revealing: When McClane goes into the icy room in the power station, look at the pipe to the side of him: it's in shot a few seconds and you can see that the writing on the pipe is reversed, revealing that in the editing room, the shot was flipped.

Factual error: During the chase with the semi, McClane is shown struggling to keep the truck under control with the freeway collapsing/blowing up all around him. He is shown making a left turn on a ramp, and the truck going up on 9 wheels, almost rolling. The shot cuts back to McClane steering left to to try to control the truck. If he were to steer left, as depicted, he would be guaranteed to roll the truck. If he was trying to get the wheels back down, he'd have to steer into the roll, or right, to bring it back on the wheels. At the end of the shot, you can actually see the stuntman brings the wheels down with a short right turn of the steering wheel. The similar entry in corrections is right, the person making the correction is wrong. During 15 years of driving a semi, I had a very similar situation with the truck almost rolling. I had to steer into the roll to bring the truck back on the wheels, not away from it, as the film showed McClane doing.

Other: Where does the fire in the gas pipes come from? Even though a lot of gas - and thereby pressure - is directed towards the power station, why do they blow up under ground far away from the power station?

Continuity: John throws Matt to the floor when Matt is first being shot at. John lays on Matt to protect him and you can see that John's legs are off to Matt's left and are lying flat on the floor. The scene cuts to a view that's from behind their feet and now John's legs are no longer flat on the floor, his lower body is turned and he is lying on his right hip.

Continuity: Near the start of the chase involving the HAZ-MAT van and the semi, John runs into a black Mercedes Benz car, skewing it round to the left of the cab, later on in the chase, he hits exactly the same Mercedes.

Continuity: In the scene when Bruce Willis is driving the police car up the ramp to blow up the helicopter, the guy jumps out. As he jumps out he has got headphones on, but when he lands on the car they fall off. The next scene it shows him taking them off.

Continuity: John's face is all bloody after he rolls from the car and "kills a helicopter with a car". The blood on his face constantly changes during the shots. Sometimes there is blood all over his face, sometimes there is quite a bit less. Sometimes he has blood streaming from the cut on his nose, sometimes there is nothing on his nose. The blood changes back and forth, so it's not just him wiping the blood away from his face (and his hands are by his sides during all the shots).

Continuity: When McClane and Farrell are fired upon during the escort to DHS, Agent Johnson is killed and slumps against the steering wheel. In the next shot he is alive, looking back through the car's rear windshield, and jolts forward with the car's impact with the car in front of them.

Factual error: In the street scenes of Washington, DC, the cabs are Yellow Cabs. DC does not have a yellow cab system, but rather "gypsy" cabs that come in all colors. There are actually very few yellow-colored taxi cabs.

Audio problem: During the final chase scene when McLane takes control of the semi truck, you can hear the truck continuing to shift gears even though McLane is not completely in the driver's seat and nowhere close to the clutch or shifter.

Continuity: When McClane first brings Farrell to the Cyber division, McClane has a cut over his eyebrow that he gets from a fight scene later in the film. [This mistake is pointed out in the DVD audio commentary: this scene was filmed after said fight scene was completed.]

Continuity: McClane's head wounds move around throughout the movie. Especially the two red spots on the left side of his head change colour a lot.

Continuity: When the terrorist holding Lucy is shot in the foot, it is very clear that Lucy is wearing sandals, but when we see her feet from under the van as she kicks the gun to her dad, she has brown boots instead.

Continuity: When the truck crashes into the pillar that McClane and Matt are hiding behind in the tunnel, we see a large portion of the pillar fall off from the left side. However, when McClane gets up to drive the police car, the pillar is in perfect shape.

Factual error: When McClane drives the SUV into the elevator shaft, you can see where the windshield has been "smashed out". There are wavy clean breaks along the perimeter of the lucite used as the glass. In reality, a windshield would shatter but still hold together in one sheet. It's impossible for it to break cleanly like shown in the scene.

Plot hole: Just after the F35 shoots most of the top off of the cab and the back of the semi truck McClane is driving, there is a camera shot that pulls back from the front of the truck that shows large 1-foot diameter holes in the top of the engine compartment. The first problem is that the plane's bullets came from the side, not the top (not down through the engine hood) and the second problem is that the engine shouldn't still be running with multiple 1-foot holes shot into/through it - yet the truck continues to climb the incline.

Continuity: At the end of the scene where Bruce Willis's own car is involved with a crash between a dustcart and taxi you can see his driver's door opening during the aerial shot after he has left the location.

Continuity: In the scene after the power plant explodes and Farrell is giving his "What is the point?" speech, his hair changes several times between shots, from hanging down in front of his face to being swept to one side.