Was totally banned in France until 1981, upon request by Yvonne De Gaulle, Charles De Gaulle's wife, then president of France, scared that the film might open a recurring debate over antisemitism.
Although Claude Chabrol is credited as supervisor for the film, he wasn't actually involved. He accepted to be credited only to bypass censorship laws : Marc Boureau's film wouldn't have met the censorship requirements otherwise.
The apartment owner is named Charles, a reference to by then president of France, Charles De Gaulle.
During the roll call scene at the end of the movie, the numbers used to call the characters are actually French social security numbers (created in 1940, easily recognizable as the first digit is 1 for men and 2 for women).
The ending sequence prefigures John Carpenter's They Live, as the characters are surrounded by TVs displaying black on white messages as "Buy on credit" or "Have children" (but also paradoxically "Be on the pill").