When Mills is hijacking the police car, the car is hit twice. First from in the front and then in the back, but later the car is seen driving with no damage at all.
In the scenes shown during Stuart St. John's description about Oleg Malankov's security, the Bentley Mulsanne changes into a Bentley Continental as it enters the building.
When Bryan is being chased by the police in the beginning, he escapes them by going under a truck and falling into the sewers. He is completely sub-merged in the water, but when he is back outside his shirt is wet up to the collar.
Lenore's Audi R8 Spyder is seen near the start of the film. This is the revised model and has no registration plate. After she visits Bryan, she drives away in the original model, which has a different light design and a large registration plate. This car is also seen again later at Bryan's home.
The jet's flight crew request a clearance to takeoff on Runway 2. A subsequent shot shows them departing runway 5L.
When Bryan hijacks the Police car two of the plain clothed cops open fire on the car. With one of their uniformed officers still inside? This just would not happen as it would of course endanger the life of the officer.
When Stuart goes to the Malibu house, he enters a Mercedes Benz S-Class 550 5th generation (W221). During Bryan's chasing him., you can see that it turned to a 6th generation S-Class (W222.)
While escaping the police in the school, Bryan throws a non-lethal grenade, which produces smoke, which then causes the sprinklers to activate. Sprinklers are activated when heat causes a soft metal bar to melt, opening the water valve. They are not activated by smoke.
When Brian calls Kim after escaping from the police, and when he hangs up, we hear a dial tone on Kim's line. Kim's phone is an iPhone, which doesn't have the normal dial tone sound at the end of a call.
The Russians twice use the word "suka." Each time, the translated subtitle reads, "scumbag!" Suka is not the Russian word for scumbag. Suka (cyka) is literally the Russian word for "bitch." In Russian criminal jargon, suka refers to anyone who is cooperating with law enforcement or government authorities.
After smashing into the front landing gear of the jet, the Porsche show zero damage in subsequent shots.
At the end Bryan Mills is driving a Porsche 996 Carrera and it seems that he is driving really fast. Normally the spoiler would appear at about 75 mph, but there is no spoiler visible.
In the beginning of the movie when Malankov's men are kidnapping the accountant, Maxim tattoo is visible inside the house, but when they are outside the house, the tattoo is no longer visible. The tattoo it is only visible again when the safe door is being closed.
When the cops rush into Malankov's Building, the Chevy SUVs are Euro-Spec (you can see side-turn-signal). When a cop says, "Lock it up. Nobody in, nobody out," there is a Rolls-Royce Ghost with black plate "YW 9961" which is obviously not a US plate.
At the end when Bryan Mills is driving the Porsche, the police officer announced the letters in the plate as Mary Jane Charlie, the NATO phonetic should have been Mike Juliet Charlie.
In the early scene where Lenore is in Mills' apartment, he hands her a spare key. The head of the key shows it to be a Kwikset. A trained operative like Mills would never use a Kwikset lock for his apartment -- they are among the cheapest locks available. A man with a background (and potential enemies) like his would use a much higher-security lockset, such as Medeco, or Schlage Primus.
Just after 1hr 20min at police station, the cops are reviewing the backgrounds for the good guys. At the first shot of all the guys' sheets, it says 6'4 and 215 weight, (same height and weight as Liam Neeson's character) then snapping back it changes to "actual" stats.
Just after 1hr 20min at police station, the cops are reviewing the backgrounds for the good guys. At the first shot of all the guys' sheets, it says the same height & weight for all of them, then snapping back to each one, they change to "actual" stats.
When Bryan Mills reaches the door of Malankov's suite and fires a few rounds at one of his henchmen, you can see the metallic looking plate on his chest where special effects squibs are located.
Stuart calls the airport from his car and says he'll be there in 15 minutes. The only way someone could get from downtown L.A. to Santa Monica in 15 minutes would be via teleportation. Moments later, Bryan turns onto the northbound 110, which would send him in the opposite direction from Santa Monica, toward Pasadena.
Some details show us that the Mountain Chase was shot in Europe : You can see some Triangle Warning Sign on the road. US Standard Warning Signs are 45-degree-tilt Squares. The Crew just hang some US Standard Signs to cover the EU-Standard signs. However, they just left a few. And if we observe them from the back, you can see they were "US cover EU".
When Kim is being tailed by the police detective we see a billboard for Willie A. Watkins Funeral Homes which is located in Atlanta, GA not LA, California.
When the Porsche is shown approaching the Santa Monica airport, the surrounding area is a desert. Santa Monica's airport is in a heavily urban area.
While the flight crew requests clearance for runway 2, and a subsequent shot shows them entering runway 5L, Santa Monica Airport has only one runway: 3 (from the south-west) / 21 (from the north-east).
Stuart makes the elevator security sound impressive, and it appears to work that way when he gets in. But every subsequent elevator access works like any normal public elevator.
In the police station, signs misspell Police Department as "Police Departement," using the French spelling of the word.
When Kim goes to select her yogurt it is previously mentioned in the film that she always takes the fourth one from the back. When she actually selects her yogurt she counts four from the front. As well as this being an error it would also potentially lead her to selecting the wrong yogurt, not the one left to her by Bryan.