John Wayne broke his leg during filming, causing a three-week delay in the production schedule before shooting resumed in Rome at Cinecittà Studios, where interior sequences were shot.
The desert scenes were filmed in Libya. The end credits state: "The locations photographed for this film were in the United Kingdom of Libya." The location shooting for Legend of the Lost (1957) took place near Tripoli. The lost city of "Timgad" referred to in the film was the Leptis Magna ruins, a Roman city dating back to the 7th century B.C. near Tripoli, in northwest Libya, while "Timbuktu" was Zliten, Libya. Headquarters for the film were located in Ghadames, where citizens of the villages were employed on set, as well as some native Tuaregs, an ancient desert tribe.
In his autobiography Jack Cardiff recalled that on the first day of shooting John Wayne, who was supposed to be playing a Foreign Legionnaire, arrived on location wearing a cowboy outfit. When he asked director Henry Hathaway why this was, he looked at Cardiff as if he were mad and exclaimed: "He ALWAYS wears the cowboy outfit!"
The Roman ruins where the action take place are the ancient city of Leptis Magna in Libya, which is not in the middle of the desert, but at the very coast. In fact, the shot where the viewer sees a front view of the Roman theatre doesn't show the building's full height, so as not to reveal the sea in the background.
In a documentary about British director of photography Jack Cardiff, it was said that director Henry Hathaway was not respectful to the English members of the crew. He did not, for example, like their penchant for taking breaks for tea.