"Lux Radio Theater" broadcast a 60 minute radio adaptation of the movie onMay 3, 1948 with Lilli Palmer reprising her film role.
Dan Seymour became friends with director Fritz Langon the set of the movie after Lang discovered he spoke German. Seymour maintained a life-long friendship with Lang and became the executor of Lang's estate.
Gary Cooper's role was based on the real life exploits of Michael Burke, who would later become President of the New York Yankees.
A twenty-six episode radio serial of the same name was produced by NBC in 1950. The radio show was also suggested by the Corey Ford and Alastair MacBain book that was the inspiration for this film. The radio program commenced by Raymond Edward Johnson asking the question, "Are you willing to undertake a dangerous mission for the United States knowing in advance you may never return alive?"
According to the book 'The Films of World War II' by Joe Morella, Edward Z. Epstein and John Griggs (1973), "This film is significant because of its attitude and treatment of the subject of nuclear weapons...In the version seen by the public the film ends with Gary Cooper completing his mission, rescuing the Italian scientist and accompanying him back to the Allies. He leaves Lilli Palmer behind him but it is implied he will return for her after the war. Director Fritz Lang has said that in the original ending the scientist dies on the plane and the British and U.S. secret service men must further pursue the Nazis. From a photo left by the scientist they surmise that the Nazis have an installation in Bavaria. They find the site has been abandoned and there is dialogue to this effect: 'Probably the plant is in Argentina now - or somewhere.' Lang has stated that the final fadeout had Cooper walking out of the abandoned cave seeing an American soldier. The sun is shining, birds are singing and Cooper says, 'This is the Year One of the Atomic Age and God help us if we think we can keep this secret from the world, and keep it for ourselves.' According to the director, the entire fourth reel was cut and probably doesn't exist any longer. He assumes that Warners cut his ending because it was too soon after the bombs had been dropped on Hiroshima
Anti-atomic bomb dialogue was removed before release.
Due to military intelligence and secrecy reasons, American Hollywood Studios were prevented by the US Government from mentioning the OSS (the Office of Strategic Services) in movies during World War II. However, this movie was first released in September 1946 which was after the end of World War II, hence explaining why the OSS was mentioned in this movie.
This movie's opening prologue states: "This picture has been inspired by the amazing achievements of the OSS the Office of Strategic Services, but no part of it is intended as a portrayal of actual events. The story, names, characters and events depicted are wholly fictitious. If there is any similarity between them and any persons living or dead, or any events which may have happened, it is entirely coincidental."