Continuity mistake: When John is fighting the gang men at the start we see him crouching over the unconscious body of a thug. John then looks up and dives out the way of the speeding car, however the unconscious thug has disappeared when the taxi hits John's car. (00:11:50)
Continuity mistake: The damage to John's car at the start is constantly changing. For example, he reverses into a car and smashes the rear of his car up. A few seconds later it's in perfect condition. (00:09:00)
Continuity mistake: When John arrives at the Continental, we have an overhead shot showing two doormen to John's left. Camera changes to behind John and now those two doormen are suddenly talking to someone in a blue suit. (00:26:50)
Continuity mistake: When Santino places the metal item on the table after saying John will always be that man, there is a white item on the table next to it. As John pushes it away, the white item has disappeared. (00:22:40)
Continuity mistake: After the motorcyclist crashes into John's car, in the wider shot all John's headlights are on, then as he gets out, all but one are off. (00:02:15)
Continuity mistake: At the beginning while John is talking with Winston at the hotel, the sun changes between shots. (00:28:00)
Deliberate mistake: One of the bodyguard's rifle which is a Sig model SG553 only has a front sight and no rear sight. The rear sight can easily be attached to the Picatinny rail. Such a rifle is only good for up close instinctive shooting, anything at distance is spray and pray. (01:39:00)
Continuity mistake: When walking along the cars at the start, John is level with the first car. Camera changes and now he is level with car 2. (00:06:45)
Continuity mistake: When the motorcycle hits Wick's car during the chase scene at the start, the motorcycle demolishes the front right quarter panel and door, with noticeable pieces hanging off the car. When Wick walks around the car to investigate the driver, the car appears to be in pristine condition. (00:02:05)
Revealing mistake: When John is escaping at the start, he throws a sharp left when a taxi appears ahead of him. Just before he takes the turn, we see a view from in the car. In this shot, you can see skid marks already ahead of him exactly where he's about to skid. (00:08:20)