Continuity mistake: The Audi car is missing its W12 logo in the grill in one shot. In different scenes with the Audi, there are two different number plates at the front (at least where the number plate were supposed to be: one with two "holes" at the lower end, and one without. Obvious that there were 2 different cars used.
Revealing mistake: Near the end of the movie, the car is driving up to the business aircraft as it is taking off. In one of the flashes of the aircraft, the engine reverse thrusters are engaged. This only occurs on landing. They must have filmed the scene in both takeoff and landing phases of flight, only intending it to look like the plane was taking off.
Other mistake: When Frank shows up at Audrey's house, the cops are patrolling the grounds for security reasons. One cop sees that a glass pane in the french door has been smashed, to allow an intruder to unlock the door from the inside. But when the cop opens the door, we see that there is no lock, or even a latch, on the door.
Factual error: When the plane crashes into the water, both men in it should have flown towards the front of plane due to the sudden deceleration.
Continuity mistake: At the doctor's office, Lola shoots up a police car, damaging the passenger doors, and destroying the light bar on top, then steals the car. When arriving at Audrey's house, to get into Frank's car and kidnap the kid, the police car she is driving has an intact light bar on top. When Frank leaves the driveway, and accelerates away, the police car is hit, but once again the light bar is shot up, and there are bullet holes in the passenger side doors.
Continuity mistake: In the scene where Frank's fighting the guards with the fire hose, one of the last guys to attack him (in a red shirt) runs up very close to the Frank, who then backs away maybe 5 feet. In the next shot that same person with the red shirt is now about 15 feet away and charging toward Frank.
Continuity mistake: During the final battle, after Frank and the bad guy roll around the plane the first time, Frank pins him against the wall and punches him. But in one shot his hands flip and he is hitting him with the opposite that he was in the previous shot.
Continuity mistake: At the very end of the garage scene, Frank picks up his gun from the floor and it's noticeably different (more resembling a Desert Eagle) than the gun he dropped.
Deliberate mistake: In the doctors surgery, Frank protects himself with a door from Lolas shots, yet the bullets don't penetrate the thin plywood door. It can't be a fire door because you can see inside the door through the holes made by the bullets.