The Flash Guide: Cast, Runtime and Where to Stream

A multiverse film that spends its reset wisely

The premise is simple and the execution is not. Barry Allen uses his speed to change one moment in his own past, and the film spends its two hours on what breaks when he does: a world with two of him in it, a Justice League that never formed the way he remembers, and a General Zod invasion with no Kryptonian allies left to stop it. The time-travel mechanics are simpler than they sound and the film explains them early, so none of what follows requires tracking rules across scenes.

The film’s reason to exist is the two Batmans. Michael Keaton returns to the role for the first time since 1992’s Batman Returns, playing a retired, older version of his 1989 performance rather than an imitation of it, while Ben Affleck closes out his run as the DCEU’s Batman in the same film. Putting both in one story, rather than treating either as a cameo, is the clearest sign of what the film is actually interested in: not a new threat, but a farewell tour through the DC films that came before it.

That farewell framing turned out to be literal. The Flash was the last film of the Snyder-era DC Extended Universe before James Gunn and Peter Safran’s relaunched DC Universe began with Superman (2025), so watching it now plays less like a mid-franchise entry and more like a closing chapter for Affleck’s Batman, Michael Shannon’s Zod, and the Snyderverse’s version of these characters altogether. For the film most directly tied to it, Zack Snyder’s Justice League is the clearest before-picture; for where Gotham went next, our The Batman guide covers the separate, unconnected version of the character. The film’s production record has full cast and release details, and everything else we track by release date is in our watch guides.