Colonel Blimp was a British cartoon character in a then well-known strip. The producers decided to use the name for the movie.
The filmmakers wanted Laurence Olivier to play Clive Candy, but he was prevented from being furloughed from the Navy by Prime Minister Winston Churchill, who didn't want the film to be made. Churchill didn't want to bolster the production with an actor and star of Olivier's caliber, as he felt the movie was critical of a type of British patriot. Olivier was allowed to take a leave from the Navy to make a film about William Shakespeare's patriotic King Henry V in Henry V (1944). Roger Livesey was cast instead. A generation later, he played Olivier's father, Billy Rice, in The Entertainer (1960), though he was actually less than a year older than Olivier.
Director Michael Powell was intrigued by how second-unit cameraman Jack Cardiff was filming the animal heads and gave Cardiff his first big break as the cinematographer on his next film, A Matter of Life and Death (1946).
Three-quarters of the Germans in the crowd at the POW camp are carefully painted and positioned plaster models.
Roger Livesey did not gain any weight for the Turkish bath scenes. His pot belly was a very convincing prosthesis designed by Stuart Freeborn.