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)

John Wick (2014)
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Directed by: David Leitch, Chad Stahelski
Starring: Keanu Reeves, Willem Dafoe, Michael Nyqvist, Alfie Allen
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Viggo Tarasov: I heard you struck my son.
Aureilo: Yes, sir, I did.
Viggo Tarasov: And may I ask why?
Aureilo: Yeah, well, because he stole John Wick's car, sir, and, uh, killed his dog.
Viggo Tarasov: Oh.
Trivia: Chad Stahelski, the director of the John Wick films, had worked as Keanu Reeves' stunt double for 15 years prior to his directorial debut on this film.
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Answer: No. Regardless of any cancellation that Viggo made after-the-fact, the "Cardinal Rule" still applies to Marcus. He accepted the contract, he was contractually-obligated to kill John Wick, and he failed to kill John Wick. Marcus broke his word, essentially, which was an inexcusable violation.
Charles Miller