The opening scene has a matte shot with the U.S. capitol dome in the background. The dome was not completed until 1866.
Released the same year as Gary Cooper's most famous Western High Noon (1952), which also starred Lon Chaney Jr. in a secondary role.
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.
Most of the actors are armed with the Colt Single Action Army (SAA) model of 1873, specifically the cavalry model with the 7½" barrel.