Entire story had been filmed as a silent, minus a soundtrack, by Howard Hughes in 1928. Greta Nissen had the role played later by Jean Harlow. When sound equipment became available Hughes decided to re-shoot the whole film as a talkie.
All color prints of the movie were thought to be lost until a print was found in John Wayne's personal vault in 1989, ten years after the actor's death, by his son Michael Wayne. That explains why the younger Wayne's name appears on the credits of the restored version. It is possible that Wayne received the print from the film's producer/director, Howard Hughes. The actor starred in Jet Pilot for Hughes in 1949, but the film was not released until 1957 because Hughes continued to have the flying sequences re-shot, a situation not unlike this film.
Although it has been reported that Hughes re-shot all the silent material, that seems unlikely looking at the footage shot in the dirigible. The voices are out-of-sync and some of the action seems hurried, suggesting it was shot at a silent speed of 18 frames per second, rather than 24 fps sound speed and dubbed later.