At about 1:10 while counting during a rehearsal, Harriet skips the 6th count of 8.
At about 1h 45m into the film, during the curtain call, those dancers were standing at different positions from different angles. Watch for the two men who were wearing blue and red bodysuits, they were standing at different places.
When Ry gets out of the bath behind the screen, it's clear she's wearing a body stocking.
After the female dancer finishes her solo, a single male voice is clearly heard shouting "Bravo!" from the audience. The correct word is "Brava", the feminine of bravo.