I recently finished reading Patrick McGilligan's massive biography, 'Fritz Lang: The Nature of the Beast.' It was so big and overly detailed, I almost didn't make my way through it. I can only think even St. Martin's Press is cutting down on editors.
But there were some interesting bits. The set for Lang's film 'The Spider Woman' was constructed in the Hagenbeck Zoo in Hamburg (the first modern zoo, where its founder Carl Hagenbeck revolutionized animal training). His 'Lady in the Moon' (a sci-fi classic from 1931, which he co-wrote with his then wife, Thea von Harbou) invented the countdown (yes, that 5-4-3-2-1 countdown). Having decided that Peter Lorre would whistle the 'Hall of the Mountain King' from Grieg's 'Peer Gynt,' he didn't like the way Lorre whistled, so the whistle in the movie is Lang himself.
When he was working in Hollywood, Brecht had to keep the same twilight curfew that other enemy aliens did.
And finally, von Harbou became an enthusiastic Nazi (she stayed when Lang fled to Paris). After the war, she served time in prison, and labored as a Truemmerfrau, separating usable bricks from bad in Berlin's rubble.