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As noted in the film's credits, exteriors for the picture were shot in Switzerland. According to Hollywood Reporter news items, 60,000 feet of film was shot there in August 1946. Sir C. Aubrey Smith, who plays "Col. Hugh Banning" in the picture, narrates part of the story, as does Warren Douglas, as the character "Jeffrey Stevens." Although Minerva Urecal is listed in reviews in the role of "Miss Woodley," onscreen credits list Mary Field in that part. Hollywood Reporter news items add Carl Ledell, Albert Moser, Gordon Armitage and Bill Martin to cast, but their appearance in the completed film has not been confirmed. In February 1947, Hollywood Reporter announced that composers Lucien Moraweck and Rene Gararrasgune, were "to be used to prepare" the film, but only Moraweck is credited with music in the onscreen credits and in reviews.
High Conquest was produced shortly before the announced start of RKO's mountain-climbing film, The White Tower, which was also based on a James Ramsey Ullman book . RKO postponed production on The White Tower, in part because of feared competition with High Conquest; The White Tower was finally made in mid-1949 and released in 1950. Swiss cinematographer Tony Braun, who is credited with exterior photography on High Conquest, also worked on The White Tower. According to a New York Times article, while producer-director Irving Allen was filming High Conquest in Switzerland, he shot footage for a short documentary called Climbing the Matterhorn, which was released by Monogram in 1947.