The opening scene has a matte shot with the U.S. capitol dome in the background. The dome was not completed until 1866.
According Ben Mankiewicz of TCM, while the crew was filming on location at Lone Pine, California at the base of Mount Whitney, a mushroom cloud from a nuclear device was seen on the horizon coming from a Nevada nuclear test site. The test site was operational from 1951 until 1992.
At 53:56 a Wilhelm Scream is heard when a Confederate soldier is killed with a sabre.
Released the same year as Gary Cooper's most famous Western Matar ou Morrer (1952), which also starred Lon Chaney Jr. in a secondary role.
Executives at Warner Bros did not want Gary Cooper to play the role, fearing his wholesome image would not suit a plot involving cowardice and double-dealing for both sides in the American Civil War. Director Andre DeToth insisted Cooper should be cast, and Warner Bros gave way.