Revealing mistake: The saloon's upper level railing looks solid until just before the bad guy falls through it, when the cuts in the break-away section are prominently visible. (00:26:05)
A Thief is a Thief (a.k.a. Magnificent Thief) - S1-E1
Continuity mistake: When Mundy and Claire are sitting in the car outside the apartment building, the rear view mirror has disappeared (probably removed to prevent it from obscuring the actors' faces). It mysteriously reappears later on. (00:42:45)
Noah Bain: Oh, uh, look, Al, I'm not asking you to spy. I'm just asking you to steal.
Alexander Mundy: Let me get this straight: you want me to steal?