Suga decided that he needed surgery on his shoulder while doing the dance choreography in front of the stairs (from Suchwita ep.104 with Hoshi: "Ironically, I ended up getting shoulder surgery because of 'Black Swan' and 'ON'...In 'Black Swan', there’s a move that goes like this. After doing it, I could barely move my arm")
Theatres are definitely weird and creepy after hours. Run, BTS! Get out of the creepy, beautiful theatre!