Continuity: 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.

Factual error: In several chase scenes that take place in Washington DC McLane and Farrell are driving around the city with buildings that are at least 40 to 50 stories tall. This is impossible as the Height of Buildings Act of 1910 prevents any building being any higher than 20ft more than the width of the street the said building sits on. The buildings seen in the chases are much too tall for this city to actually be Washington DC.

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.

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?

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: 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: 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.

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.

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.

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: When John and Mai are fighting at Woodlawn, John tosses Mai up against a glass board. Her pony tail has come undone and her hair is a big mess. You see Mai from the back as she gets up to come after John. Her hair is now neatly combed and back in a pony tail. But as she begins to fight, her hair is once again undone and messy.

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.

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.

Deliberate "mistake": In the US theatrical release, at least three times during the film, you can see that what the characters are saying doesn't match up with their mouth movements. This is of course to censor some of the more profane language to secure a PG-13 rating, but still a mistake.

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: 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.

Other: If the natural gas could be rerouted to McClane's position at the national grids control center, there are two major problems. The gas would not self-ignite on it's way there as pictured and secondly, the sheer momentum of that massive amount of gas in those long pipes would cause a massive leak at the endpoint. However, after the first (relatively small considering the total energy in all the gas) explosion everything goes back to normal without one giant amount of gas erupting.

Factual error: The "police" radios shown in the police cars are actually amateur band radios on an amateur band frequency.

Audio problem: After the terrorist in the helicopter opens fire on John and Matthew, a policeman yells something about backup into his radio. What he's saying doesn't match up with his mouth.