Continuity mistake: When John first meets Marcus in the cemetery, John's umbrella changes from a standard 8 rib when lowering the coffin, then a 22 rib close up, then back to 8 ribs in a far shot of the two men shaking hands. (00:04:15 - 00:05:45)
Other mistake: When John is talking to the club bouncer, John says that he lost weight, to which he replies (in Russian) "Twenty kilograms." The translation says "over sixty pounds," but 20 kilograms is just over 44 pounds. (00:46:30)
Suggested correction: Maybe he's actually saying "Over 20 kilograms" in Russian. If you calculate the other way 60lbs is just over 27kgs.
Logically that doesn't make a lot of sense since the mistake is saying the translation says "over 60 pounds", so we have to assume by 20 he means over 27.6. Why not just just say "over 27 kg"? And you appear to just be guessing that maybe he says "over 20 kg" in Russian.
Watching it literally right now... he absolutely says "20 Killogramma".
Continuity mistake: Just when John Wick puts the bracelet on the night table next to the phone near the start of the film, the time changes all of a sudden from 8 to 10. (00:04:00)
Continuity mistake: The holes that Ms. Perkins puts into the glass above John's bed keep disappearing and reappearing. This is not to be confused with the extra bullet hole mistake already listed. (00:55:50)
