Alain Delon was originally cast as Cervantes.
Spanish star Soledad Miranda filmed many scenes in addition to the ones shown in the final cut of the film. This is apparent in numerous publicity stills of scenes cut from the film. In a magazine interview, it was revealed what happened to her scenes. Soledad and Horst Buchholz were on set together, and some French journalists were driving around set taking photographs. They published a photo of Miranda and Buchholz together in Le Figaro, which Gina Lollobrigida then saw. It caused Lollobridiga great jealousy, who wielded her star power to have all but the most essential of Miranda's scenes cut from the film.
Vincent Sherman's last film. Blacklisted by Hollywood, he would direct for television until his death in 2006.
King Vidor did preliminary work preparing a biographical film on Miguel de Cervantes and ended up combining his resources with this European production. However, for unclear reasons Vidor disassociated himself with the picture that would become "Young Rebel."
In 1964, Anthony Quinn was announced for the role of Hassan Bey.