This is a fascinating if flawed film. Made during the war and shortly after the actual assassination of the hangman of Prague Heydrich, it is clearly propaganda for the war - it was shot in 1942, released in 1943.
Could be compared to the wonderful WENT THE DAY WELL made the same year, the first ever film based on a Graham Greene short story, to mention a Nazi invasion (lots of speculative novels and films since).
In reality Heydrich was not shot but died a week after a grenade exploded under his car in Prague. SO watch the extra here, a German professor with wonderful English explaining the history and context for half an hour.
Fritz Lang made classics like Metropolis (1927) silent film and the brilliant 'M' which made the German actor Peter Lorre a star - great films both.
Of course, there are many cartoon characters here, caricatures of Nazis, partly because it is anti-Nazi propaganda and partly because many silent film stars and directors did that - see Chaplin.ls the Great Dictator. That care get tiresome these days.
Some classic shadows and angles of Lang's German Expressionism too, making Nazis characters seem sinister just from shadows.
I am sure Mel Brooks was influenced by this to make THE PRODUCERS (original title Springtime for Hitler) - the OTT caricatures for one, but also the music, the song at the end - reminds me so much of HERE'S HITLER in that musical!
A great watch, esp for war film fans, maybe a tad long but 3.5 stars rounded up.