I interviewed Donald OConnor for my radio show back in 1992, super nice guy, He related this story about Make Em Laugh, He was off set for 3 days after shooting the sequence, when he came back there was much applause and praise for his performance. Then Gene Kelly took him aside, and asked him, you think you can do it again? The footage was destroyed for the first take! https://www.google.com/amp/s/www.thevintagenews.com/2017/12/13/singin-in-the-rain-trivia/amp/
Interesting stuff, thanks