Rodd Redwing, a fast-draw artist, was a Technical Advisor and worked with Robert Culp on this movie. Redwing suffered a heart attack on the plane returning from filming in Spain, and died shortly after landing in Los Angeles, California.
Quentin Tarantino has said this movie was one of his inspirations for Kill Bill: Vol. 1 (2003) and Kill Bill: Vol. 2 (2004). "Why I love Hannie Caulder so much is Robert Culp," he said. "He is so magnificent in that movie. I actually think there's a bit of similarity between Sonny Chiba (Shin'ichi Chiba) and Uma Thurman in Kill Bill and Raquel Welch and Robert Culp in Hannie Caulder."
The production company, Curtwel Productions, was owned by Raquel Welch and her husband at the time Patrick Curtis.