Nancy Olson hated the script, but figured six weeks in Hawaii and a chance to work with an icon like John Wayne seemed like a good enough reason to accept. Besides, she thought the film would flop and nobody would see it. She was right, to a degree: it wasn't one of Wayne's more successful pictures, but she didn't count on the constant television exposure it has had, and says people stop her all the time to say they've seen her in the film. Olson, a staunch liberal Democrat, said she and Wayne would often have political arguments, but she would always let him have the last word.
The German title is "Mathuana". In this dubbed version for the German market, John Wayne played a hunter of marijuana smugglers, not an investigator for the Un-American Activities Committee ferreting out Communists, as in the original film.
John Wayne was one of the most vocal Hollywood supporters of blacklisting and McCarthyism, even personally offering to identify Communists for the FBI.
John Wayne recorded an advertisement for Camel cigarettes on the set. Wayne had smoked 3-5 packs of cigarettes a day since the early 1930s, and later developed lung cancer, necessitating major surgery in 1964.
The first film produced by Wayne-Fellows Productions (later renamed Batjac Productions), John Wayne's independent production company.
Edwin Layton: was arranged by the studio as a favor for getting permission for John Ford to film the actual Midway battle. Layton was the Pacific Fleet's Fleet Intelligence Officer at Pearl Harbor on December 7, 1941.