"Ain't We Got Fun", wasn't performed until 1920 and published until 1921. In the movie it is shown being sung before 1920.
When Trudy and her coach, Bill Burgess, are sitting on the beach, Burgess mentions meeting the queen after swimming the channel. He completed his swim in 1911, 10 years after Queen Victoria died and 15 years before Queen Elizabeth II was born. The English monarch at the time was King George V.
Despite being in a ticker-tape parade with a whole bunch of CGI confetti in the air, not one piece lands on any of the actors.