Warning: This post contains spoilers for The Flash

The Flash, the latest installment in the DC Extended Universe out in theaters Friday, is all about multiverses, time travel, and multiversal time travel. As Barry Allen a.k.a. The Flash uses his super speed to travel back in time to stop his mother from being killed, he meets multiple Batmen (in a nod to the multiple Hollywood heavyweights who have played the role of Batman over the years) and learns what happens when you mess with history.

The Flash is the second-to-last movie in the current DCEU. Aquaman and the Lost Kingdom will mark the final installment before co-CEOs James Gunn and Peter Safran overhaul the DC film and TV universe. It’s unclear whether the Flash will return to the screen—or if Ezra Miller, who plays the superhero, will be recast in the role. Gunn has said The Flash will “reset” the DC Universe and that all the characters “will be connected.”

Here’s what happens at the end and in the post-credits scene of The Flash.

What happens at the end of The Flash?

The Flash is on a journey to prevent his mother (Maribel Verdú) from being killed—in turn, exonerating his father (Ron Livingston), who was accused of her murder. He shares his plan with the Bruce Wayne of his universe, played by Ben Affleck. Wayne advises him against the idea because, as multiversal stories go, messing with the past means potentially disrupting events in the future. Barry doesn’t listen to Batman and time travels anyway, meeting an alternate version of himself after successfully saving his mother. Therefore, the original Barry and, well, Barry meet Michael Keaton’s Batman, who explains to them that time is not linear and that changing events won’t just affect one point in time but events prior to that moment and beyond. It’s a confusing concept, but the effects of Barry’s actions become clear by the movie’s end.

After, Barry realizes that to ensure the safety of the space-time continuum, he has to travel back in time again to undo his own damage. At the end of the movie, he is able to get his dad to look at the security camera in the grocery store by rearranging items on the shelves, which corroborates his alibi, helping his father get acquitted and out of prison. Waiting at the courthouse, Barry receives a phone call from Bruce Wayne, who congratulates him on his father’s victory and says he’s pulling up to the courthouse. As Wayne steps out of the car, reporters and paparazzi crowd him. Barry, back in his own universe, is expecting Affleck’s Wayne to walk out of the car, but it turns out to be George Clooney. “Now, who the f-ck is this?” Barry asks, as the movie ends.

What is the significance of George Clooney’s cameo?

Clooney played Batman in the 1997 movie Batman & Robin, replacing Val Kilmer, who played Batman in 1995. Kilmer replaced Keaton, who donned the Batsuit in 1989 and 1992.

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Gunn has said that a new Batman and Robin movie is in the works as part of Chapter One in the revamped DC Universe. He said the movie will be centered around Batman and his son, Damian Wayne. While no casting announcements have been made for any of the films in the DC Universe overhaul, Clooney’s appearance in The Flash suggests he might reprise his role as the Caped Crusader. Our guess is that this is highly unlikely.

What happens in The Flash’s post-credits scene?

A post-credit scene shows Barry taking a drunken Aquaman (Jason Momoa) out of a bar and trying to lead him back to his apartment to sleep it off. The drunk superhero falls face-first into a puddle and tells Barry to go and get more beer while handing him one of his rings. Barry refuses at first, saying, “This is Atlantean treasure,” before he obliges anyway, and walks away with the ring. It seems inconsequential but adds some excitement for Aquaman and the Lost Kingdom, expected in theaters this December.

While Michael Keaton was announced to make an appearance back in April when a trailer for the movie was released, it kept some of its significant cameos under wraps, especially the biggest one at the end.