Continuity mistake: When Stuart is leaving the building, he enters a previous generation Mercedes Benz S Class. The next couple of shots where he is being followed by Bryan shows the newly redesigned S Class.
Factual error: Towards the end of the film, where St. John is trying to escape with Kim in his private jet, they are apparently attempting to take off from Santa Monica airport. When the camera shows the aircraft beginning its take off roll, the runway markings show that they are using runway 05L to take off from, however, the two runways available at Santa Monica airport are 03 and 21. (01:33:00)
Factual error: The police release Bryan once it is proved he didn't kill his wife. However, they ignore the multiple murders committed by Bryan (for example, he killed bodyguards that were just doing their job), easily injured - if not not killed - many innocent bystanders in a variety of action man moments (freeway pileup, parking garage explosion, etc) and resisting arrest twice.
Continuity mistake: When Bryan calls to Kim to tell her mother is dead, at the beginning she has no socks but few seconds later when the talk is finished she's wearing one black sock.
Character mistake: When Dotzler is giving one of his first meetings when trying to catch Brian in the police station, the LAPD signs behind him are misspelled "Departement."
Continuity mistake: On the highway, the police car he's in is struck twice on the back end. Impact actually pops the trunk. When the car drives off, there's no damage to the car.
Audio problem: When the police are about to handcuff Liam Neeson, he says "I didn't do this", but his lips don't move.
Factual error: The movie is supposed to take place in CA, but when Kim pulls into the parking lot of the convenience store for her smoothie, a billboard for Willie A. Watkins funeral home is visible. Willie A. Watkins funeral home is a very prominent Atlanta, GA business, where filming took place.
Continuity mistake: When the police are watching the funeral, Kim hugs the 2nd man with her right arm over his shoulder and around his neck, and her left arm behind his back. When it cuts to the surveillance camera, Kim's right arm is lowered and holding his arm.
Factual error: After Brian calls Kim to tell her that Lenore is dead, he hangs up and there is a shot of Kim. We hear a busy signal on her phone instead of a dead line.
Factual error: When Liam puts the police car in reverse in the garage and backs into the elevator shaft, the speedometer goes up to 80mph. Speedometers don't work in reverse.
Continuity mistake: When Liam jumps in the water from under the truck, he goes completely underwater. When he is walking through the wash, his sweatshirt is half dry. (01:25:45 - 01:27:06)
Revealing mistake: When the car goes off the road, there is CGI smoke which is visible above the tinted window, but is missing from through the window which isn't completely blacked out.
Continuity mistake: When the Russian was coming down the steps in the apartment shootout he has on black bottoms, but when he is shot they turn white.
Continuity mistake: When Oleg is dying on the stairs in his apartment, we can see his back is resting on the fourth step. A couple of seconds later his back has somehow relocated to the third step after death.
Character mistake: Liam calls his daughter's boyfriend Timmy, then a minute later he calls him Jimmy.
Plot hole: When Bryan goes to the Russian bad guys' heavily-guarded apartment/office building, they make a point of saying that a guard upstairs monitors a camera and operates the elevator allowing only certain people to come up. Brian manages to trick the elevator operator into letting him up, then proceeds to kill him and all the other guards on the way to the apartment. How does he end up using the elevator to get back down when everyone is dead? And who is letting the cops up to the apartment when they show up well after everyone had been killed?
Answer: I saw it as they needed Bryan out of the house to stage Lenore's body. Lenore had already been kidnapped the previous day and now they needed to plant her body in his home.
Bishop73