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.
Factual error: 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.
Factual error: Natural gas flows through a pipeline due to pressure differences. The main line is held at a high pressure, usually 600 psi or more, while the end user is at a few pounds or less. You can not "send all the gas" to a particular location. No matter how much you raise the pressure in the main line it will only flow through the open valve at the end users location.
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.
Factual error: The "police" radios shown in the police cars are actually amateur band radios on an amateur band frequency. (00:34:20)
Factual error: There are no toll booths, tunnel or otherwise in the area of Washington D.C. where the anti-helicopter car launch is supposed to have taken place.
Factual error: When Gabriel turns off the lights in the tunnel, we see a shot of cars heading towards the police car as the lights turn off, and not one of them turns its headlights on. In reality, with that many cars in the tunnel, there'd be at least one that was fitted with auto-lights.
Factual error: Just after Bruce Willis slides down the ramp, and gets up to walk away, there is a car that supposedly fell off the highway. This car is turned upside down. It is obvious that the transmission and drive shaft have been removed from the vehicle, making it undrivable. (01:56:15)
Factual error: 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 its way there as pictured, and 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: 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.
Factual error: In the beginning of the movie after the scene where John watches his daughter go inside, he is called on his police radio. The gentleman on the other end is in fact talking to him on a land-line telephone and not a radio, but from Johns end you hear the mic being keyed on and off. Police radios cannot make or place telephone calls and vice-versa. (00:06:45 - 00:07:50)
Suggested correction: Although very unpopular and very unlikely to have been installed in a Police car, some radios can indeed ring landline telephones. They were known as "Mobile Radio Telephones" but they tended to be extremely unreliable.
Factual error: Just before the power plant explodes we are shown a scene where the natural gas pipeline is exploding on it's way to the power plant. The first explosion (while not actually possible) would have destroyed the pipeline and no more gas would have flowed to the power plant and therefore the power plant could not explode.
Factual error: When McClane "kills" the helicopter with the police car, as shown in the film, the car runs up the toll booth like a ramp and smashes into the helicopter. However, if you look, though the slab on the side is ramp-shaped, it is about 2 feet off the ground, so realistically, the car just should have smashed into the booth rather than shoot over it.
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.
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.
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.
Factual error: The hazmat van is shown to be a Mercedes Benz. The problem is that in 2007, when the movie was shot, this was sold by and as a Dodge. It was only sold as a Mercedes from 2010 onwards. Presumably it was rebadged as part of a product placement deal. (01:48:55 - 01:51:50)
Factual error: The cyber attack takes place on the 4th of July which is a national holiday, the stock market is closed and so are government offices, no politicians are meeting at the Capitol.
