Factual error: When Tuco is in the gunshop messing around with the guns, one gun has the cylinder and barrel moving back and forth by manipulating the trigger guard-lever. This is a Belgian Galand & Somerville revolver, a gun that did not exist until 1868. This film takes place during the US Civil War, which ended in 1865.
Factual error: When Angel Eyes arrives at the Confederate Army Hospital, the Confederate flag that is flying is not the correct flag; it is the flag that people in the 20th century and later think of as the Confederate flag. The only rectangular flag with the blue St Andrew's cross on red was the Confederate navy flag and the battle flag of the Army of Tennessee, which was the standardized battle flag for the Western Armies (but not that far west) after January 1864, so didn't exist in the New Mexico campaign, nor at the time the story takes place.
Factual error: Extended version. After finding a dying Bill Carson, Tuco arrives at an outpost looking for a hospital. It's night, or at least dark outside - he is told the hospital is 18 miles away. In the next scene he arrives at the hospital at nearly high noon. A horse canters and gallops (full speed) between 4-30 mph. Basically the hospital was an hour away.
Add timeBeau Peterson