Snyder's Justice League ends on a doozy of a cliffhanger, which he always intended to do, even if he is not making any future DC movies.
"The ask was for my version of the movie," he told The New York Times of his decision to keep his original ending, which (spoiler alert!) was set in the future. In it, Wonder Woman (Gal Gadot) and Aquaman (Jason Momoa) are dead and Batman (Ben Affleck) is aligned with a surprising new group: The Flash (Ezra Miller), Cyborg (Ray Fisher) Meera (Amber Heard), Deathstroke (Joe Manganiello) and, most surprisingly, his arch-nemesis the Joker, with Jared Leto reprising his role from Suicide Squad (and teasing he had killed Robin). The big bad we discover they are facing? None other than Superman (Henry Cavill) in the wake of the death of Lois Lane (Amy Adams), a tragedy that was foreshadowed by a future version of The Flash's alter ego Barry Allen to Bruce Wayne in Batman v Superman, though Barry reveals he's "too soon" with his warning.
"I added it because this was going to be the last movie I make for the DCU and to have this entire cinematic universe without Batman and Joker meeting up just felt weird," Snyder said of the shocking sequence. "Jared and I had a bunch of conversations about it. I had mentioned it to Ben and I was like, Ben, let's just do it at my house. I could shoot it in the backyard. Don't tell the studio and I'm not going to pay you guys. I'm just going to shoot it myself."
Snyder didn't have to resort to Guerrilla-style filming though, noting in his Times chat, "What happened is it worked out and we were able to do it for real. And then I called the rest of those cast members and said, Hey, would you guys be down to come around and do it."
And if he had the chance to continue telling the story, Snyder detailed what would've happened next:
"It's the fall of Earth, when Superman succumbs to anti-life," he revealed. "And then sending Flash back in time to change one element so that doesn't happen. And then the big battle where we beat him. When [the villain] Darkseid comes to Earth, in the movie that you'll never see, the armies of Earth all unite again, as they did before. This time there would be aircraft carriers and Special Forces guys, all the armies of the world would come together, as well as [Aquaman's fellow] Atlanteans rising out of the ocean and the Themyscirans [Wonder Woman's compatriots] coming off their island. That was our big finale. But it's a long drum roll and guitar solo to get there."