Joker is one of the biggest movies of 2019. It's right on the cusp of joining the billion-dollar club (it's currently at $993 million worldwide), has wowed audiences and critics and generated a ton of discussion as to its themes. One element of the film that's generated a lot of debate though is whether the final scenes take place in Arthur Fleck's head. It's a question that's worthy of discussion, too. After all, we see Arthur suffering delusions earlier in the movie and his sudden acceleration from complete nobody to inspiring a riot and being adored by a crowd is very sudden.