- Creator Backlash: Gary Cooper had been displeased with the script, and pointed out that a Confederate soldier would be working for Emperor Maximilian, not for Benito Juarez.
- Dawson Casting:
- 54 year old George Macready plays Emperor Maximilian I of Mexico, who should have been 32 in the time period the film was set in.
- Gary Cooper was fifty-two at the time of filming, although his character was only supposed to be a couple of years older than Burt Lancaster's character. Joe Erin was meant to be forty, Lancaster's actual age.
- Hostility on the Set:
- Gary Cooper hated working with Sara Montiel, who he claimed smelled bad and never washed her hair.
- In his biography, Ernest Borgnine reports that, during the shooting, Burt Lancaster brought his children on the set and all of them laughed at Jack Elam because of his walleyed eye. Elam, of course, was upset because of this, and he had a tough argument against Lancaster in a fierce fist fight.
- Wag the Director: Burt Lancaster recalled that Gary Cooper would object to anything in the script that implied his character was anything other than good (despite the fact that he was playing a former Confederate Colonel, who fought to maintain slavery), and demand it be changed.
- What Could Have Been: Screenwriter Borden Chase wrote this with John Wayne in mind.
Trivia / Vera Cruz