Other mistake: At the end of the "We Can Do It" scene, the Checker Cab the stars get into is a late model. It is definitely not the same vintage as the other 50's model cars in the movie. These cabs appear in various other street scenes.
The Producers (2005)
1 other mistake - chronological order
Directed by: Susan Stroman
Starring: Will Ferrell, Matthew Broderick, Uma Thurman, Nathan Lane
Continuity mistake: When Max Bialystock is singing "Along came Bialy", and the old ladies start coming out of the apartments, the first lady who comes out isn't there in the next shot.
Leo Bloom: Mr. Marks, you were right about one thing. You are a CPA. A Certified Public ASS-HOLE.
Trivia: Mel Brooks "composed" the music for the Broadway show (which would go on to become this movie) by humming tunes into a tape recorder. Someone who was musically literate would then write it down on staff paper.