Other mistake: In the song "A Rumor in St. Petersburg," according to the closed captioning, the characters sing the words "no proof of fact." According to the lyrics in the soundtrack booklet, they are actually singing "or through a crack." And if you listen, it's actually what they are saying.
Other mistake: In the shot where the elevator door opens after the screenwriter hears the music playing, the control panel (for the basement) shows the building goes up to eleven floors. When the elevator opens on Floor 5, we can see the control panel on this floor only goes up to ten floors, despite being in the same building. (00:41:55)