Nancy Olson hated the script but she figured six weeks in Hawaii and a chance to work with an icon like John Wayne seemed 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 TV 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 Wayne have the last word.

John Wayne recorded an advertisement for Camel cigarettes on the set of Big Jim McLain.

Edwin Layton has a cameo that 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 7 December 1941.

Many scenes filmed in public places such as the restaurant scene with Gordon Jones appear to be "stolen", as the bystanders seem to be watching the scenes being played out rather than act like extras who normally do not pay attention to the action.

The first film produced by Wayne-Fellows Productions (later renamed Batjac Productions), John Wayne's independent production company.

The German title is "Mathuana". In this dubbed version for the German market John Wayne plays a hunter of marijuana smugglers, not an investigator for the Un-American Activities Commitee ferreting out Communists, as in the original film.