Following the attack on a luxury liner by a German submarine, two Allied war ships are seen steaming to the datum. One is HMS Relentless (H85); the other is USS Preble (DD 345).
This was the first film to be granted the production seal of approval under new guidelines set forth by the Production Code Administration Office and the Motion Picture Producers and Directors of America. The modern US ratings system continued its numbering system, which granted certificates to over 40,000 titles by the mid-2000s.