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.

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: 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: 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.]

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: 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: 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).