The Flash

Barry Allen never got over the murder of his mother, Nora, for which his father, Henry, was convicted. He discovers he can run back in time and, against Bruce Wayne's advice, saves Nora. On the way back he gets stuck in 2013, in a reality where he shares life with his younger, powerless self. It's the day Zod arrives on Earth, and there's no Superman, Wonder Woman or Aquaman. They find a retired Bruce Wayne, played by Michael Keaton, and instead of Kal-El they find Kara Zor-El. The battle with Zod ends badly again and again. Barry realizes some things can't change, lets his mother go and tweaks just one detail, which clears his father. When he returns, he finds reality isn't quite the same.

• After the credits Barry helps a thoroughly drunk Arthur Curry out of a bar and tries to tell him about the different Batmen he met across the multiverse. Arthur falls face-first into a puddle.

1. ReferenceThe Superman that never was

   As the multiverse collapses, Nicolas Cage appears as Superman fighting a giant spider. It's a nod to Superman Lives, Tim Burton's Cage-led film that was canceled in the '90s.

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2. ReferenceYou wanna get nuts?

   Michael Keaton repeats "You wanna get nuts? Let's get nuts," the line he improvised in 1989's Batman.

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3. Behind the scenesGotham is in Scotland

   Batman's opening motorcycle chase was shot on the streets of Glasgow, and Edinburgh also stood in for Gotham. Gotham police cars roared down St Vincent Street.

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