- Executive Meddling: Originally planned to be shown in single lens Cinerama with reserved seat roadshow engagements, Columbia pulled the plug on that idea, and the film was drastically cut down immediately prior to its release, from nearly three hours (plus an intermission) to just over two hours.
- Fake Nationality: Omar Sharif (an Egyptian) and Keenan Wynn (of Jewish-Irish background) as Mexicans; Julie Newmar (of Swedish-French descent), Ted Cassidy, and a few other obviously Caucasian actors as Apache Indians (hidden under layers of brown makeup).
- Old Shame: Gregory Peck hated the film:
“Mackenna’s Gold was a terrible western. Just wretched.”
- Paying Their Dues: The making of this movie was documented in a short film directed and written by a young film student named George Lucas.
- What Could Have Been: The film was originally meant to star Clint Eastwood, but he was busy with Hang 'Em High. Steve McQueen was also considered.