Joaquin Phoenix improvised "large parts" of 'Joker' by reacting to the score in real time

"There are some scenes that didn't exist in the script" Joaquin Phoenix in Joker Joker‘s composer has revealed that “large parts” of the movie were shot to her score, and that the cast improvised scenes to the music she composed. The movie recently became the most profitable comic book movie ever, as well as the highest-grossing R-rated movie of all time.