WHen entering Bullock's room Frank accidentally breaks a vase with his arm. However in the next shot a much bigger and more colorful vase is standing on the same spot.
When Cora stops dancing for Bullock the tape recorder with the song she was dancing to stopped automatically as well, without any action, even if Bullok started the recorder himself.
The uniforms of the policemen who arrested Frank resemble Russian army leader uniforms rather than actual Spanish police or army uniforms.
The story supposed to be set in Madrid. However the license plate on Bullock's care resembles a German license plate from Munich, in the combination of letters and numbers, rather than official Spanish Plates.
Earlier in the movie Frank explains that Karate should only be used as a defense technique, never as an attack. However during the entire movie there are several scenes where Frank beats up several people who didn't attack him at all, e.g. in Bullock's karate school.