'Joker' has been doing gangbusters in the box office. Aside from 'Avengers: Endgame', it's probably the most talked about movie all year.

People have been fascinated behind what went on behind the scenes of 'Joker'. Check out this blooper in which its star Joaquin Phoenix loses it at the cinematographer Lawrence Sher.

Well that wasn't all we didn't see.

One of the movie's most tragic moments is when it is revealed that Joker, aka Arthur Fleck, had never had a relationship with Sophie (Zazie Beetz). He made the whole thing up in his head.

The revelation comes when Sophie finds him in his apartment and threatens to call the police. The scene then cuts to Arthur walking down the hallway, the fate of Sophie left ambiguous.

According to Sher, director Todd Phillips "makes it clear she wasn’t killed." He says: "Arthur is killing people who’ve wronged him in a certain way, and Sophie never wronged him."

Phillips reiterated the same to Indiewire, telling them: "He doesn’t kill her, definitively.

"As the filmmaker and the writer I am saying he doesn’t kill her. We like the idea that it’s almost like a litmus test for the audience to say, ‘how crazy is he?’ Most people that I’ve spoken to think he didn’t kill her because they understand the idea that he only kills people that did him wrong. She had nothing to do with it. Most people understood that, even as a villain, he was living by a certain code. Of course he didn’t kill this woman down the hall."

Interestingly, Phillips also told the website that originally the apartment scene wasn't going to be Sophie's last appearance in 'Joker'. The script included a cutaway shot during Arthur’s interview with Murray Franklin (Robert De Niro) showing Sophie watching the talk on television. This would have confirmed that Arthur definitely didn't kill Sophie. However, Phillips cut the moment because he only wanted the movie to be told only from Arthur’s point of view. He also felt cutting to Sophie would have disrupted the intensity and flow of the scene.