The compact pistol which Joe Moore (Gene Hackman) hides in his cup of coffee is a Baby Browning .25 caliber. It is 4 inches long, 2 3/4 inches high, and 3/4 inch thick.
Joe Moore takes a taxi about 14 minutes into the movie. The taxi is marked "Cape Ann Taxi" with the phone number 617-187-0156. Area code 617 is for metro Boston.
The Massachusetts State Police Troopers all wear plain leather gunbelts and accessories. In reality all duty gear for the Mass State Police is patent leather.
In the first visit to the airplane, the boxes are correctly depicted as extremely heavy. But when the robbers pay a second visit, to pick up the real gold in the "foundry" containers, the boxes are wheeled around too lightly and effortlessly.
When unloading the gold from the plane, the camera turns and there's a truck with 2 personnel standing next to it clearly visible under the airplane in the background. They are supposed to be alone on the taxiway.
Bobby Blane: Hey, you go to that plastic surgeon, don't you let him put you all the way under. I knew a cat in Stateville one time; went to get his face fixed. Woke up and the sucker had given him a pair of tits.