The film's horse trainer told Elliot Silverstein that the scene where a horse leans against a wall with its front legs crossed could not be shot because horses don't cross their legs, then that it might be possible if he had a couple of days. Silverstein invoked his rank as director and gave him an hour. The trainer plied the horse with sugar cubes while repeatedly pushing its leg into position, and they were able to get the shot.
Based loosely on the true story of the "Butch Cassidy and the Sundance Kid" gang, who were one of many robber bands who dwelt between heists at the Hole-in-the-Wall in Wyoming. The character of Cat Ballou is equivalent to the real life robber "Etta Place" whose true identity is unknown.
When filming the scene where Kid Shelleen takes a bath and dons his costume, director Elliot Silverstein had all actions timed to the beat of a metronome, its pace increasing when Shelleen takes his guns. He planned to have the scene scored with Spanish guitars following this beat, but the producer was adamantly opposed to anything Spanish in a Western. In the end, electric guitars were used.
Like several other Columbia releases of the 1960s (i.e., Bye Bye Birdie (1963), Strait-Jacket (1964)), this film includes a spoof of the studio logo, in this case with the Torch Lady doffing her robes in animation and turning into a cartoon cowgirl.