When Ray Milland's character views the aftermath of Custer's battle at the Little Big Horn through binoculars, footage from They Died with Their Boots On (1941)--also a Warner Bros. film--is used.
The story of the movie was composed and sung by Lee Hazlewood on his LP from 1966: The Very Special World of Lee Hazlewood (track B4).
There is a city in central California named Shafter, located in Kern County, between Bakersfield and Porterville. It is unknown whether this influenced the name of the lead character, Kern Shafter.