Character mistake: Shortly after Felix arrives at Oscar's apartment, he goes to a window and asks if it's 12 floors. Oscar rushes over, slams the window shut, and says it's only 11 floors. Since Felix had to push the button in the self-service elevator to get to the correct floor, and since he had been to the apartment many times before to play poker, he would have to know that it was 12 floors.
Continuity mistake: When Oscar and his pals are in police car number 578 out looking for Felix, suddenly they are in car 956; car 578 pulls up next to them (with real cops in it) to see what the problem is. (01:38:24)