Continuity mistake: The mural outside of the apartment switches walls - it's on the right most of the time but it appears on the left in one scene. (00:30:48)
Factual error: They are filming in Brussels and the leaving Mercedes 190 has indeed a Belgian license plate. But it is a fake plate that has a mistake... It shows 1-N82-63X but a license plate in Belgium has always a combination of 1-xxx-123 where the first part always has letters and the second part numbers. Numbers and lettters are never combined. Also it is missing the mandatory sign to prove authenticity. (00:48:30)
Continuity mistake: When the hitman tries to kill him while he is driving, he passes the silver Toyota Prius without making any contact, and 5 seconds later drives into the same Prius that had already passed. (01:09:25)
Visible crew/equipment: When Denzel is fighting the man in the back seat of his car, they pass a silver Prius, which he hits. The camera tracks alongside. You can see the camera operator. It's clear enough you can make out that he is wearing a motorcycle helmet and has gloves on. (01:09:30)
Visible crew/equipment: After burning the car, when Dave takes the trash out there is a camera operator at the end of his driveway. (01:11:00)
Other mistake: As York is entering Dave's apartment, and Dave is guiding Miles to the secure room, the entry door of the apartment appears to have only a chain lock and presumably a door knob lock. Standard stuff for apartments, and Dave surely is not relying on this for security or awareness, but It seems inconsistent with the high-tech and defense-first nature of the movie. (01:26:30)
Continuity mistake: When Denzel goes back to the flat in the Uber/Amy scene, the young lad locks the door, but when Denzel leaves, he just opens it.
Plot hole: Robert first shoots the electrical transformer on the pole's top, then enters the bakery, slices the wheat sacks and uses electrical fans to create a dust cloud for a dust explosion. How are the electrical fans supposed to work after the electricity is cut?
Revealing mistake: The final scene is filmed in Brant Rock MA, and the weather is blatantly CGI. If you notice almost everyone is bone dry in a supposed driving rain storm. Look especially at the character perched on top of the submarine tower. For contrast note the "pizza delivery" scene where it is raining heavily and everyone involved is soaking wet.
Visible crew/equipment: When the bad guys shoot the state trooper during the storm, there is a shot of the trooper falling. A crewmember creeps into frame quickly before the shot cuts.
Continuity mistake: When McCall is about to have the fight in the hotel room, the man who answers the door goes and locks the door right before the fight begins. When McCall is done with the fight, he turns the doorknob and walks out without ever unlocking the door.
Character mistake: Dave's wife refers to McCall as his "Army buddy" - but the pictures in McCall's house on the shore show him to be a Marine. Not a generalisation a Marine would make.
Continuity mistake: When Denzel is fighting with the assassin in the car, the driver's seat can is rotating between shots.
Continuity mistake: When he gets Miles from the gun gang, he has his own revolver and takes one from the guy at the elevator but when he enters the room he has an automatic weapon from nowhere.
Continuity mistake: When Robert enters the boss' room to pay for Teri's "freedom", before he goes to leave, he turns the three glass skulls on the desk to face 3 of the gangsters. After he goes to the door and locks it, he looks back at them and the skulls are now back in their original positions, facing forwards.
Continuity mistake: When fighting the guy in the back seat. Denzel initially swerved and passed the green Prius. They pass the same car again and hit it.
Answer: Extremely high winds from the storm. He was relatively protected lying down but blew backwards when he got up.