Mel Brooks cannot read music. "Springtime for Hitler" and "Prisoners of Love" (as were all the songs Brooks writes for his films) were hummed into a tape recorder and transcribed by an expert. When Brooks adapted the movie into a stage musical, he wrote the entire score by himself using the same method.
Gene Wilder said in an interview on TCM that at the first reading of the script, he excused himself to leave for a dentist appointment he could not miss, when in fact he had to go to the unemployment office to collect a check for $55 he desperately needed at the time.
Mel Brooks has said that one of his "lifelong jobs" is "to make the world laugh at Adolf Hitler." The film was a way to enact vengeance through comedy. "The only real way I could get even with Hitler and company was to bring them down with laughter," Brooks said.
Mel Brooks related the following in an interview with Larry Siegel in Playboy Magazine in 1966: PLAYBOY: What else are you working on? BROOKS: Springtime for Hitler. PLAYBOY: You're putting us on. BROOKS: No, it's the God's honest truth. It's going to be a play within a play, or a play within a film, I haven't decided yet. It's a romp with Adolf Hitler and Eva Braun at Berchtesgaden. There was a whole nice side of Hitler. He was a good dancer, no one knows that. He loved a parakeet named Bob, no one knows that either. It's all brought out in the play.
Mel Brooks says that producer Joseph E. Levine wanted to fire Gene Wilder after seeing some of the footage because he thought he "stunk." He wanted to give Mel Brooks $35,000 more to find someone better, but Brooks convinced Levine that Wilder was fine, and would make the movie work. Wilder would be nominated for an Academy Award for his performance.