This. That dance was poetry in motion, but I don’t know how they did it without violently falling on their asses several dozen times.
That’s what rehearsals, cuts, and edits are for.
And there’s lots of editing …
Shots from multiple takes are combined to create a sense of continuity but sometimes the result is a jarring discontinuity. There are several times when rain and puddles change to a dry floor, followed by a difficult dance move, and then back to rain and puddles.
In any case, the scene is a fantasy or dream sequence, right?
The opening shot has Mac with a background that is completely black. He’s supposed to be visiting his father in prison and telling him that he’s gay, in front of all the prisoners. Then, instead of talking with his father, Mac has decided that the best thing is to do an interpretative dance, because that’s the type of guy that Mac is and that’s the type of thing that his father will understand and appreciate. :dubious:
Mac appears on a dramatically-lit sound stage and starts dancing with professional dancer Kylie Shea, who is amazing. No indication of how he found her, how the dance was choreographed and staged, and when and how they rehearsed on a wet floor. The dance is very dramatic, but it’s not meant to be “real”, is it?
Well, maybe it really is always sunny *and *rainy in Philadelphia … 
In the context of the episode, it was absolutely real. He set it up with the warden, his father walked out halfway through the dance, Frank broke down in tears. It was real.