Actor Charles Buchinsky (his birth name) changed his name to Charles Bronson, using his new moniker for the first time in this film, and remained so for the rest of his acting career.

General Edward Canby, whose death is depicted in this movie, was in reality the only U.S. army general killed during the American Indian Wars. "General" G. A. Custer, killed at the Battle of Little Big Horn in 1876, was not in fact a general at the time of his death. After the Civil War, he held the permanent rank of Lieutenant Colonel.

Final fight scene between Alan Ladd and Bronson was at Slide Rock State Park

The actual fighting in the Modoc War occurred mostly in the lava beds of southern Klamath County, Oregon, and Northern California's Tule Lake area.