Factual error: It's late 18th, possibly early 19th century and, as Jane and her sister walk along the beach, a construction crane is visible on the horizon.
Factual error: Federal institutions have strict rules for inmates or patients based on the reason for their incarceration, including substituting metal utensils with safer plastic ones. Despite being convicted of brutally killing his family, Myers is still trusted with a sharp metal fork - resulting in the nurse's death.
Factual error: When Swagger is fleeing from the police in the car wash after being shot, the radio says that he is at a car wash at 9th and Girard. There is no such intersection. On Girard Ave, 9th street picks up south and north of that street.
Factual error: If you pay attention to the backgrounds of the scene where Frank is in the airport and when Frank is being arrested as he walks from the church, you can see two cars pass by which weren't produced until at least 2000.
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: When Chigurh is in the gas station talking to the clerk, behind him on the shelf is a pack of Jack Link's beef jerky. The movie is set in 1980, but Jack Link's did not start selling beef jerky until 1986.
Factual error: The uniform the female soldier is wearing when she comes back home is all wrong: the camo pattern is that of the USMC digital desert uniform but it has "US ARMY" chest tags (in a strange size and position, by the way). The US flag and unit insignia are on the wrong arms. The cut of the jacket is ACU, the pants are true USMC. (00:15:00)
Factual error: At ~9:53 into the movie, we see the newspaper with "Sunday, March 14, 1987". March 14, 1987 was a Saturday, not a Sunday.
Factual error: Firearm issues abound throughout the film. The British detectives (who all seem to be armed, rather than a low proportion of AFO (Authorised Firearms Officers) as in real life) are shown carrying Beretta pistols, even though the Metropolitan Police issue the Glock 17. The SFO (Specialist Firearms Operations) officers are shown carrying MP5 submachineguns, which is accurate, but fitted with cheap toy-shop lasers. Weapons handling is poor throughout, with chickenwing syndrome particularly prevalent. Weapons carriage also appears geared to look "cool" rather than realistic; shoulder holsters - which practically everyone wears in this film - are rarely used for concealed carry in reality.