Parts of the film were shot in Utah locations such as Snow Canyon, Warner Valley, Pine Valley, Leeds, and Harrisburg. The exterior scenes were shot near St. George, Utah, which is 137 miles (220 km) downwind of the United States government's Nevada National Security Site and received the brunt of nuclear fallout from testing active in this period. In 1953, 11 above-ground nuclear weapons tests occurred at the site as part of Operation Upshot–Knothole. The cast and crew spent many difficult weeks at the site, and producer Howard Hughes later shipped 60 tons of dirt back to Hollywood in order to match the Utah terrain and lend realism to studio re-shoots. The filmmakers knew about the nuclear tests but the federal government had assured residents that the tests posed no hazard to the public health.