The film was so financially successful it saved Warner Brothers from bankruptcy.
In the finale, dancers on stage pass a store named Reticker's. It was named after Warner Bros. art director Hugh Reticker, who labored at the studio for two decades but did not get screen recognition until two years after this film was made. It's likely he had a hand in designing this set also.
After the "42nd Street" number was completed, Busby Berkeley was promoted from weekly contract status and was given a term contract by the studio.
Ginger Rogers took the role of "Anytime Annie" at the urging of director Mervyn LeRoy, whom she was dating at the time.
At the end of the "42nd Street" number, Billy and Peggy pull down a curtain or shade with the word "Asbestos" written on it. This can be a confusing reference to 21st-century viewers, who may only be familiar with asbestos as a mineral composite which is now known to cause the lung cancer mesothelioma, but during the first part of the 20th century asbestos was an often-used flame-retardant component in building materials. It also would have been a reference familiar to theater people, since live-performance theaters were at the time required to have a curtain made of asbestos that would separate the stage from the audience in the event of an on-stage fire. In that context, the presence of the curtain in the film is the movie's way of implying that whatever Billy and Peggy are going to do behind the curtain, it will surely be "hot."