Filming began on May 6, 1949 and lasted six weeks until completion on June 20. Walsh made use of a number of locations in southern California; first by going to the Santa Susana Mountains (near his home) to shoot "chase scenes". He then moved on to an old Southern Pacific tunnel near Chatsworth to stage the opening robbery scenes. Urban street scenes along with the "Milbank Hotel" were shot in and around Van Nuys. The "hideaway lodge sequences" were shot at the Warner ranch, the interior scenes in the studio itself, and the climax scene at an oil refinery near Torrance, south of Los Angeles. The drive-in theater scenes were shot at the now demolished San Val Drive-In in Burbank.