- Creator Backlash: Charlton Heston was not overly impressed by the finished film, suggesting in his 1995 autobiography "In the Arena" that the film might have been better if William Wyler had directed it instead of Anthony Mann.
- Fake Nationality: Charlton Heston is a Spanish folk hero.
- Hostility on the Set: Charlton Heston and Sophia Loren didn't get on. Part of the reason could be that Loren was paid more than Heston (one million dollars, the first time a woman had been paid that sum for acting in a single motion picture). As can be seen in the finished film, during many of the "love" scenes, Heston refused to look at Loren for more than a glance. Anthony Mann tried take after take, imploring Heston to look into the eyes of the woman he was supposed to love, but Heston couldn't bring himself to do it. Regarding his deathbed scene, he later claimed that he was "looking into the future," rather than into the eyes of his wife. Heston later said he regretted the way he behaved towards Loren during filming, feeling in retrospect that he'd been unprofessional and unfair to her and wished he'd been kinder and less stubborn.
- No Dub for You:
- Interestingly enough, the live-action film was never dubbed in Latin American Spanish (outside a very obscure dub which no one knows exactly when or which country was dubbed and very likely was never released), since the European Spanish dub was used instead there. This is likely intentional, due to the very Spaniard setting of the film and the fact the movie itself is based in one of the most famous works of Spanish literature of all time which was originally written in Medieval Spanish, so a Latin American dub would sound out of place here.
- On the other hand, the animated film was indeed dubbed in Argentina.
- What Could Have Been:
Trivia / El Cid