I've just watched this wonderful movie on TV, and I'm wondering whether the nazi prime minister character is based on any historical nazi politician at the pre-WWII Germany.
I know the movie is based on a novel by Klaus Mann, which portrays an actual actor of the time. So, was there any actual "prime-minister" position in pre-war Germany?
Well, at the time the novel occurs, 1933, Germany was, only by name, a Federal State, more or less like the USA. The "prime minister" of the state, known in Germany as "chancellor" was held by Hitler (although he was more like a dictator than any other thing). Then, every state had his president, somewhat like the Governor in the United States. The Prussian State was the biggest and most important in Germany, with more than a half of the German Territory and population and that time. The President of the Prussian State at that time was Hermann Göring, and the character in the book is surely based upon him.
Hermann Goering. The book's more explicit than the film: an obese ex-Air Force General, Prime Minister of Prussia, in rivalry with the "propaganda minister," dating an actress, acts as Hoefgen's patron... all of which tallies with Goering and his relationship with Gustaf Grundgens.
Additionally, the movie has him quote Goering's "When I hear the word culture" comment.
I'm afraid that you underestimate the number of subjects in which I take an interest!