May be the only movie in which the leading man, Alan Ladd, is subjected to that naval punishment known as keelhauling - being dragged under the ship's keel from a rope that was looped beneath the vessel, which could end up in dismemberment or death by drowning.
A ship called the Charlotte which sailed with the First Fleet under a Captain Gilbert really existed.
James Mason claimed in his memoirs that his portrayal of the sadistic captain was based on his close study of the manner and behavior of his director John Farrow (one of Hollywood's most notorious bullies).