After the new thriller Split dominated with a huge box office win this past weekend, fans have been talking about the film's surprise ending. With its $40 million debut, it is already a profitable hit for Universal and Blumhouse, since it only cost $5 million to make, which will pave the way for a movie fans have been waiting more than 15 years to see. If you haven't seen Split yet, there will be HUGE SPOILERS below, so read on at your own risk.

Like most of M. Night Shyamalan's movies, Split is set in the director's hometown of Philadelphia, Pennsylvania. And fans got quite the surprise at the end of the thriller, when it was revealed that this story is set in the same universe as Shyamalan's 2000 hit film Unbreakable. The scene in question happens just before end credits, set in a Philadelphia diner where there is a news report playing about James McAvoy's Kevin, who's earned the nicknamed "The Horde," since he plays host to 24 different personalities. A woman in the diner recalls another strange criminal with a name she can't quite place. We then see Bruce Willis reprising his Unbreakable role as David Dunn, telling the woman she's thinking of Mr. Glass (Samuel L. Jackson). M. Night Shyamalan has since explained that this is very purposeful, and that he is planning to do a true Unbreakable sequel as his next movie if it works out. When asked by MTV if Unbreakable 2 will happen soon, he says this.

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"I think so. I think it's the next thing. I do have another idea that has nothing to do with this...Something I'm excited about as well."

During the same interview that took place on an MTV podcast, the director spoke more about his Unbreakable follow-up, teasing that it has to stand on its own like the first two movies. And he offers cast and story details. He goes onto say this.

"All I can say is this. If Unbreakable was... take the comic book thing away. If the movie is about a guy who's the only person who survives a train wreck, everyone else dies and he's the only person who survives and he doesn't have a scratch on him. How is that possible? That's our high concept. A really cool story. And then this one, it's 'Three girls get abducted by a person that has this disorder. He believes he's many people. And all of the many different personalities are saying that there's another personality coming to get them. It's called The Beast.' That's a really cool concept. This third movie needs to have its own idea. The high concept of that final movie can't be, 'It's the final Unbreakable.' There has to be something about it that makes it its own movie. These two [Split and Unbreakable] are their own movies. That's when I'll be happiest. When [the last one] is its own movie. In a way, I can say that it just can be watched by itself."

Before the surprising final scene, there was never any other indication that Split was tied into the Unbreakable story, but there has been talk of an Unbreakable sequel in the past. Back in March 2015, pop culture icon Patton Oswalt pitched an elaborate idea for an Unbreakable trilogy to M. Night Shyamalan on Twitter, and just a few months later, the director said he was "thinking about something," in regards to an Unbreakable follow-up. The director also revealed on this podcast appearance that there were originally more Easter Eggs that reference the Unbreakable characters.

"In the script, there were more Unbreakable Easter Eggs, and I had to pull them out. There were things alluding to what's happening in the city, and with the kind of the mania that is happening in the city. And it kept referencing... there was a version of the script, and I was shooting it, where they were actively battling. Mr. Glass and David Dunn. They were actively continuing to battle. And that was so distracting from the movie. Literally, the only CGI shot from the movie was like helicopters in the background, with a burning building, where they are talking in the background and [the press] reference it, and they go, 'See?' And you are wondering, 'What's going on? What's going on?' And then you get to the end. We shot that. [But] that it was going on in real time confused people. At least, in my office. 'Wait a minute? When is this? Is it the same time period, or if this 15 years later?'"

It's possible those discarded ideas may be used for Unbreakable 2, which the director confirmed earlier this week that he is going to start writing soon. Still, the filmmaker said he wasn't guaranteeing anything because he didn't know "what the demons" would do when he actually sat down to write, referring to the "demons" he confronts when he writes his screenplays. Unbreakable hit theaters in 2000, earning a solid $95 million domestically and $248.1 million worldwide, from a $75 million budget. While it's definitely not M. Night Shyamalan's biggest hit as a director, it is the one movie fans keep asking for a sequel to, and now that may finally happen, thanks to the success of Split.