While the record album of the "Tristan and Isolde" music is never shown close enough to the camera for the movie audience to see it, it either is, or has been created to resemble, a typical 78-RPM album set of the 1940's of an RCA Victor recording featuring Arturo Toscanini conducting the NBC Symphony Orchestra. The cover art greatly resembles that of a 78-RPM album pressing featuring Toscanini conducting that orchestra. Toscanini was considered the greatest conductor of that era.
Director Fritz Lang and cinematographer Nicholas Musuraca developed a revolutionary dolly for the camera that allowed for sustained tracking shots and intimate close-ups while shooting this film. Lang preferred the practice of tracking into a close-up shot of an actor as opposed to cutting to a close-up in editing. He believed the tracking close-up captured more of the actors' intimacy and emotions.
Robert Francis, best known for appearing in The Caine Mutiny (1954), is the man in the picture of Noah Larkin's (Anne Baxter) boyfriend. But, it is not his voice used for the voice-over as she reads his letter.