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: Vaughn is reading the Wall Street Journal folded in half as his limo leaves the airport at the end of the movie. The headline is facing the camera right side up, which means the folded part he is reading has to be upside down. No doubt WSJ paid for the spot and demanded their name be right side up.