In their first meeting, when Mr. Van Damm intends to exit he is smoking a cigar, but when Mrs. Henderson mentions a theater and Mr. Van Damm turns around the cigar has vanished.
Vivian van Damm is portrayed as being in his mid-60s during the bombings. In reality he was only in his late 40s.
Alec Henderson (Mrs. Laura's son, killed by a German attack on France in 1915) is said several times to have been born in 1894, and this date is shown on his headstone. In fact he was born in 1888, and his headstone does not list any date.
The unsupported, unprojected, anachronistic singing of the principals would have been inaudible beyond the second row in the Windmill, for how it was actually done at the time.
When the stage door opens a light shines out strongly which ism't natural.
The rain was falling down on the windshield in such a manor that was not realistic when Vivian and Bertie were searching for their English Rose. Their car and Vivian's driving were obviously done with green screen or in studio. The lighting of the car also gives away the phony look of the performance.
One of the extras was not singing the correct words during the closing Windmill Song. The other soldiers were singing together and he was trying to sing along. He was not successful in his endeavor.
Laura Henderson's husband died in 1919, she purchased the Palais de Luxe and turned it into the Windmill Theatre in 1931, and introduced the nude "tableaux vivants" in 1932. The movie depicts all these events as occurring after 1937.
Athough there were women of all three main hair colors, all the women showed a remarkably uniform lack of visible pubic hair. Shaving it would have been highly unlikely for the period, and equally unlikely would be that all the women have little to no pubic hair for other reasons (naturally, disease, age, etc.).
Lord Cromer was Lord Chamberlain from 1922 to 1937 and was retired before the war.
Maureen ends up in a small river or canal during a rainstorm. She is retrieved, but never goes back for her bike or her purse. Surely, a lady would go back after her purse.