The opening credits say "COPYRIGHT MCMXXXIII [1933]," but the closing credits say "COPYRIGHT MCMXXXII [1932]".
The establishing shot of Dorothy Brock's (Bebe Daniels) hotel door, on the night before the big opening, clearly shows her to be in room 831, yet, when she throws everyone out of her rooms a few minutes later, the door number is 284.
When Denning and Brock are having coffee there is a cup of toothpicks on the table. However, the orientation of the cup changes from shot to shot.
The same drinking glass (water) is used throughout the movie. The glass is first seen during the rehearsals when Peggy faints. The same glass then pops up again in Pat Denning's home/apartment when he uses it for his lapel flower/button hole, then again the exact same glass appears in Julian Marsh's hotel room, but this time after the company have moved on to Philadelphia.
When Peggy feints and is sitting down near the stage entrance; she is left being attended to by Denning and a stagehand. However, in the next immediate cut, there is now only Peggy and Denning.
The word "Premiere" on the marquee of the theatre at the end is spelled without the final "e."
The "42nd Street" finale features full size cars as well as buildings. In order to present this the stage would have had to be at least 60 feet deep and over 100 feet wide. This would be impossible in a real theater.
In the song "42nd Street" there is the lyric, "On the avenue, I'm taking you to, Forty-Second Street". However, as the name implies 42nd is a street, not an avenue, therefore, the lyric although musically fluid is confusing and a factual error.
During the ensemble number, "Shuffle Off To Buffalo," Una Merkel and Ginger Rogers perform a duet from their berth on the train. The final stanza reads.
"He did right by little Nellie/With a shotgun in his belly/How could he say No?/He just had to Shuffle, Shuffle off to Buffalo.
Ginger stumbles over the word "belly" and substitutes "tummy," which breaks the rhyming pattern. While eating her banana, Una's expression becomes one of a surprise when she hears the miscue. (Actually, this is an intentional gag: Rather than say the coarse (for the times) "belly", Ann (Ginger Rogers) quickly substitutes the more genteel "tummy", and Lorraine (Una Merkel) reacts with mock shock to her almost saying "belly".)
For all the songs Al Dubin wrote the lyrics and Harry Warren did the music. However, at the beginning of the first rehearsal, there is a close-up of sheet music containing the melody and harmonies for the song "It Must Be June", and handwritten on top is "WORDS & MUSIC BY HARRY WARREN".
After the chorus line is told to report the following morning for rehearsal; there is a close-up shot of the sheet music for the song, "It Must Be June". The next shot then picks up the chorus ensemble singing on the 7th music staff which is a series of quarter notes. However, if you follow the sheet music, the chorus ensemble sings three more additional bars than indicated on it. They sing the lyric "June" four times however the music notes on sheet music indicate that it is only sung once.
The Finale in the dress rehearsal is considerably different than the finale in the opening night performance.
During the "Buffalo" number, Bebe Daniels and Clarence Nordstrom both wear hard soled shoes, but their routine in front of the sleeping berths is silent.