"Tell me something, you can go anywhere you want, right? Any timeline, any universe," the voice over begins. "Why do you want to stay to fight and save this one? You change the future, and you change the past."
As the video ends, Batman appears on screen with Ezra Miller joined by a second Flash and Calle's Supergirl.
Directed by Andy Muschietti, The Flash will see Barry Allen racing through the multiverse, rubbing elbows with not only Ben Affleck's Batman but Keaton's Bruce Wayne, too. (Keaton played the part in 1989's Tim Burton-directed Batman and its sequel, 1992's Batman Returns.)
"It just is harder. And it's not like that's necessarily my signature. That's not my thing -- he's the action guy! -- you know? I do it here and there," Keaton shared. "I am fortunate in that I take pretty good care of myself -- I stay basically in decent shape -- but then you get older, and you have to bump it up and bump it up. It just gets hard and there is no way around it. But it's kind of the challenge, isn't it? It's kind of the fun challenge."
Muschietti and screenwriter Christina Hodson previously teased what fans could expect from the upcoming film.
"It's a time travel story," Muscietti said at last year's DC FanDome: Hall of Heroes panel, with Hodson adding, "Batman lost his parents, Superman lost his planet, Harley Quinn lost her egg sandwich, but Barry, he's the only one who can go and change his personal story."
"[It's] the combination of giant spectacle action and fun with this incredibly personal intimate story of a boy who's just trying to save his mum," Hodson added, teasing: "I'm also excited to see Andy's version of Speed Force. They are literally unlike anything you've ever seen before."