Clive Candy goes to Germany to fight a duel over propaganda about the British treatment of people in South Africa in the Boer War. Many of the cited things he was dueling over were in fact true. "Concentration camp" was first used to describe British camps in South Africa in 1899-1902.
According to the directors, the idea for the film did not come from the comic strip by David Low, but from a scene cut from their previous film, One of Our Aircraft Is Missing (1942), in which an elderly member of the crew tells a younger one, "You don't know what it's like to be old."
Towards the end of the movie, Candy's assistant Murdoch, played by John Laurie, tells Candy that he has joined the Home Guard. 25 years later Laurie would go on to play Pte. Frazer in all 80 episodes of Dad's Army (1968), a British sitcom revolving around the misadventures of the members of a local group of Home Guard during World War II.
One of the earliest films to directly refer to The Wizard of Oz (1939) (one of the characters sings part of "We're Off To See the Wizard"), proving rather conclusively that "Oz" was more successful and popular on its first release than is sometimes claimed.