In several of the scenes in Mexico, a large smoke cloud is seen on the horizon. At the end of the movie smoke is shown rising from a volcano. This is most likely a fortuitous eruption of the Paricutin volcano in 1947, when the movie was filmed, standing in for the eruption of Popocatepetl on Cortez's day.
Alfred Newman's score is one of the earliest soundtracks to be released as a separate album. It consisted of 18 minutes of music on three double-sided 78-rpm records.
Alfred Newman's "Conquest" theme was adopted by the University of Southern California athletic teams.
Feature-film debut of Jean Peters playing the role of "Catana Perez," who later married industrialist Howard Hughes. NOTE: She had never acted before this film. She replaced Linda Darnell, who was originally cast in the lead but shortly before production began, was taken off the picture and given the lead in Ambre (1947), replacing inexperienced lead actress Peggy Cummins. Peters was given the lead in this picture based on a screen test she had taken at Fox just a week before filming began that had impressed the film's producers.
Fox chief Darryl F. Zanuck was so appalled when he saw Tyrone Power playing against type in the gritty Le Charlatan (1947) that he immediately pulled the film and rushed this film out earlier than he intended.