Continuity mistake: In the scene with the lovely dancing ladies, Cotten blows cigar smoke just before a cut to him from the opposite angle. From this angle there is no smoke. This takes place just before Wells throws his jacket to Cotten.
Continuity mistake: When the dancing girls start singing to Charles Kane, there is a frontal shot of Kane sitting next to a man wearing a hat. When the shot changes from being in front of them to being behind them, the man is suddenly no longer wearing the hat. When the shot changes back, he is once again wearing the hat.
Continuity mistake: When Kane is talking to Miss Alexander on her sofa the dramatic lighting changes from the left side of his head to the right. During close ups his left site is lit and his right side is in the dark. When the shot is from the front, showing both actors, Kane is lit from the right leaving the left half of his face dark.