Continuity mistake: In the opening scenes where he gets his mustang back, he hits the guy who comes over the roof and busts the windshield, but in the very next shot the windshield is pristine. (00:07:45)
Continuity mistake: When John and Cassian see each other through the fountain, they start to shoot at each other when the water comes back up. You hear the civilians around them start to scream and panic, but when the next shot cuts to John shooting through the water, the civilians are walking casually around calmly as if nothing is going on, but then in the next shot they are all running frantically. (01:17:45)
Factual error: The entire NYC subway platform/subway knife fight between John Wick and Cassian appears to have been filmed in the Port Authority Trans-Hudson (PATH) system that goes between NYC and NJ rather than the Mass Transit Authority (MTA) subway system (you can actually see the PATH logo on the exterior of the train cars). The PATH does not go to any of the subway stations announced on the public address system during the knife fight. (01:18:45 - 01:22:50)
Factual error: After John Wick's house blows up, he takes his dog for a long walk into the Continental in Manhattan. He lives in New Jersey and walks into Manhattan over the Brooklyn Bridge which is on the complete other side of Manhattan, crossing over into Brooklyn and not New Jersey. (00:26:45)
Character mistake: Once Santino and Ares find John again in the hall of mirrors, John is fighting two of the grunt men that came in with Ares and kills them. Both of which had light assault rifles and weapons on them. John and Ares proceed to empty their pistols out at each other before she runs off with Santino. John then throws his empty pistol away and gets up to pursue his target unarmed and while limping. It is unreasonable to think that someone with his skill and training and experience would not take two seconds to reach down and pick up one of the guns dropped by the two men he just killed before chasing after his target, especially given the highly trained body guard with him accompanying his target. As well as probable encounters with more grunts. To add to this, he was seen doing just this moments before when he had limited ammo and each time he'd down a few enemies he would pick up one of their guns and continue. (01:41:30)
Continuity mistake: On the subway during the fight between John and Cassian the other travellers in the background constantly change in both position and number, sometimes there are 2 sometimes there are 4, and although they are seated their seated position changes between shots. (01:21:20)
Continuity mistake: John shoots Santino once and gun slide locks open, showing gun as empty. In scene prior, John specifically checks gun and pats down Ruby Rose to get a fresh mag (and pockets a second) before heading to Continental.
Revealing mistake: In the beginning of the movie, when John get his Mustang, he starts accelerating deliberately to hit one of the cars (black sedan), but right after the odometer scene (where you see the gas going up) you actually see the car is stopped. It is pretty obvious. (00:09:30)
Continuity mistake: While John talks with Winston at the park the sun changes between shots.
Continuity mistake: On the subway while John and Cassian eyeball each other, from the front there's no-one in front of Cassian, just a guy in a hat off to the side. But from the back, another man appears between them.
Suggested correction: You can see the edge of that guy cut off on the edge of the shot he is there, that grey hair and that same jacket.
Continuity mistake: When John gets out of his car at the very start, he is on a zebra crossing. When he gets back in, the car is no longer on the crossing. It's hard to tell, but the car has moved. (00:02:00)
Suggested correction: The car is still on a zebra crossing, when John gets back in. Stripes are very obvious.
Factual error: The party in honour of Gianna, Santino's sister, is held at the Terme di Caracalla (Baths of Caracalla). That site belongs to the city of Rome, and would never be used to host a private party, let alone a party in honour of a major Mob figure. Moreover, the place where John and Gianna meet while she's about to take a bath is the Horti Sallustiani (Gardens of Sallust), which are some 5 km away from the place where the concert is being held.
Continuity mistake: The damage to the car after it gets smashed in the beginning the damage to the car is different to when he pulls into the driveway. (You can really notice when looking at the damage to the headlights in particular).
Audio problem: When John and another bodyguard/hitman are walking in a crowded subway/train station, and they're shooting at each other with suppressed 9mm or 45 ACP handguns across swaths of people and the people not reacting is an absurdity. High caliber handguns meaning anything larger than a .22 still makes a loud noise when suppressed. People in a general vicinity could still hear a noise and a pop. The only truly silent handgun is a .22 and it still makes a noise when the slide reciprocates back and forth. (01:18:00 - 01:18:45)
Continuity mistake: Before John starts to shoot Cassian by the fountain the blood on his left cheek increases and also the wound on that side gets smaller.
Continuity mistake: The amount of blood on John's right ab decreases when he is in the subway after the violin girl shot him.
Continuity mistake: When John enters the Continental with his dog, there is a female bellhop starts walking behind him. However she disappears instantly. (00:26:50)
Continuity mistake: When Santino says he's sorry about John's wife, he's looking at one photo that has got a sparkly frame. When the camera changes, the frame is now wood effect. (00:20:20)
Continuity mistake: Just before John shoots the Russian in his kneecaps, he is thrown flat on the floor. When the camera changes he is sat up. (00:11:40)
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)