Although set in London, the film was mostly made on Hollywood studio sets. However, a second unit was sent to London to film backgrounds, and in these scenes a double was used for Danny Kaye, mostly filmed from behind or from a distance. The double was in fact a well-known British actor and comedian, Jon Pertwee. This may account for the fact that a character called "Sir Pertwee" appears in Kaye's subsequent film "The Court Jester", also made by the team of Melvin Frank and Norman Panama.