Marlon Brando in his autobiography says that Gillo Pontecorvo was one of the three best directors he ever worked with. The other two were Elia Kazan and Bernardo Bertolucci.
Evaristo Márquez, who played rebel leader José Dolores in the film, was not an actor, but rather a poor villager from San Basilio de Palenque, Colombia, whom director Gillo Pontecorvo discovered while scouting locations in that country. He convinced Marquez to star opposite Marlon Brando, though the studio had originally wanted Sidney Poitier.
The setting of the film is a fictional sugar cane-producing Caribbean island named "Queimada." In the original script, this fictive island was part of the Spanish empire, which would have been a more accurate historical conceit, since Spain, rather than Portugal, was the dominant European power in the Caribbean. The Spanish government of Francisco Franco pressured the filmmakers to alter the script, and since Portugal accounts for a considerably smaller share of international box-office receipts than Spain, the producers did the economically expedient thing by making the Portuguese the bad guys. No Portuguese is actually spoken in the film, but rather various forms of Spanish. The original conceit is still reflected by the characters having Spanish names and speaking the Spanish language.
When working conditions became impossible in Cartagena, Colombia, Marlon Brando insisted that the film be finished and paid for the production to be moved to Morocco. Even though there was less than two weeks on the schedule, the film was finished in Morocco.