The film is based on the art style of famed French comic book artist Jacques Tardi, but not on one of his actual works. Instead, Tardi was brought in at the earliest stages by his friend and sometime collaborator Benjamin Legrand, to come up with the look of the film and the characters.
There are two glimpses of a dalek in the background of the government weapons research centre.
The start of the film shows Napoleon IV succeeding his father Napoleon III as French Emperor, and due to his weakness and ineptitude, makes peace with Prussia, ending the Franco-Prussian war. In reality, Napoleon, Prince Imperial served in the British Army during the Zulu War, where he was killed in action in 1879.
The film takes place in 1941.