Pifias

While scouting the police station, Dortmunder is mugged of his watch with the wide leather wrist band. However, when they leave the police station by helicopter, the watch is back on his wrist.

(at around 59 mins) While scouting the police station, Dortmunder is approached by a mugger who takes an interest in his watch with the wide leather wrist band. The mugger is a couple feet from him. However, when the shot cuts to Dortmunder's view of the street, the mugger is seen walking out of a doorway on the far side of the street.

During the initial conversation between Dortmunder and Kelp in the car, when the camera is on Dortmunder, his window is rolled up and no wind is apparent. Whenever the camera cuts to Kelp, however, Dortmunder is seen in the foreground with his hair being blown vigorously by an obviously open window.

Dortmunder has the key to the safe deposit box, but Abe Greenberg goes to the bank expecting to open the box and to do that he would need the key.

However, earlier Greenberg had mentioned that he is well known at the bank and has been tipping employees there for years. So it is logical that the safe deposit staff would likely allow him access without him having his key.

A couple minutes after Murch crashes his car and staggered from the wreck, a man tells the guards that an ambulance is not necessary as he has passed away. However, a few minutes later, Murch is alive and in pain.

Either the man was not a medical professional or he was taken in by Murch's acting.

When the locksmith is attempting to unlock the case in the museum, he's using only a pick. Without a tension wrench, there's no way to turn the lock cylinder, so he would never succeed in picking the lock.

The Swedish 9mm SMG used is by no means realistic. They are both fitted with the special barrel and security equipment used for firing blanks for this actual type of SMG - plastic bullets that disintegrates when fired - only used in combat training.

The police uniforms in the movie are two-tone, light powder blue shirt and dark navy blue pants. The powder blue shirt wasn't introduced in New York City police uniforms until 1973, the year after this movie was released.

When Murch crashes the yellow Mustang at the museum, a roll ramp can be seen as the car approaches as well as a cable attached to the driver's side frame of the front of the car, probably to prevent the car from actually hitting the building.

When lifting the diamond's case, the crew is not wearing gloves - their fingerprints would be a dead giveaway.