So, this scene is interesting, because it's right after a life-changing cataclysmic event in Arthur's life.

And he's found this little, kind of rundown park bathroom to go in and collect his thoughts and get himself together.

What's interesting about this scene to me is it's entirely different than what we had scripted.

In the script, Arthur was to come into the bathroom, hide his gun, wash off his makeup, and staring at himself in the mirror, like, "What have I done?"

And when we got to the set on the day, Joaquin and I just sort of stood around, like, huh... this doesn't really seem very Arthur.

Why would Arthur care to hide his gun?

And we really kind of tossed around a million ways to just do something different.

And it was about an hour into it, and I said, "Hey, you know, I got this piece of music from Hildur..."

Hildur Gudnadottir is our composer, and she'd been sending me music throughout, while we were shooting.

And I just wanted to play Joaquin this piece of music and...

Joaquin just started to dance to the music, and it was just me and him alone in the bathroom.

There's 250 people on the crew waiting outside.

And he just starts doing this dance, and we both kind of look at each other and said, "OK, that's the scene."

It made sense to us because when I first met with Joaquin and we first started talking about "Joker," I talked to him that Arthur is one of those people that has music in him.

So music and dance became a theme in the film.

And this is the second time we see him dancing, and it's a little bit of Joker coming out, a little bit more than the scene before and a little bit less than the next time we see him dance.