Deliberate mistake: When Bullitt enters the hotel room to do a Recki, we see photos of the injured man on the wall. From this we can conclude one of two actions. 1: The ambulance crew took so long to arrive, the police had plenty of time to take a variety of photos from many angles. 2: The police did not let the medics in until they had taken their photos of a man who was in need of immediate medical attention. Wouldn't the injured man rather have his wounds seen to first than his photo taken?
Deliberate mistake: When Fagin shakes Oliver's hand (when he first meets him) there is a blonde haired boy standing right behind Oliver, but in the shots from behind him, the boy is gone. This may be because the camera is just behind where the boy was and he had to move so they could get the shots from this angle.