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: Smith and the team come down the mountain and into the village at dusk, yet it is light out during the entire movie.
Deliberate mistake: The hiding of the fatal wound of Cheyenne was completely unrealistic. He couldn't return from the train on horseback and hide the wound till the end. The fact of having a fatal wound was not fitting the last Jill-Cheyenne conversation scene, but they still wanted to force it into the story as a symbol of the dying of the Old West.