No doubt a huge selling point for fans to catch a screening of The Flash film had to have been the highly-anticipated return of Michael Keaton's Batman, who finally reprisied his iconic role for the first time as The Caped Crusader since Batman Returns in 30 years.
By now, many of us are familiar with the alternate endings The Flash film had prior to DC being put under new leadership by now co-CEO's James Gunn and Peter Safran, as the original ending would have seen Keaton's Batman, and Sasha Calle's Supergirl much alive following the events of the Flashpoint timeline, and being integrated in the DC universe as a result of Barry Allen fixing the timeline.
This original ending would have kept Keaton in the DCEU, and play a more sharpened mentor-like figure to the more inexperienced superheroes of the DCEU -- the plan was for Keaton to serve as the "Nick Fury" for the DCEU going onwards. This new role would have been most evident in the now cancelled Batgirl solo-film, as Keaton's role would have been a "pivotal cameo"; popping in and out throughout the film as a now retired Batman.
Reportedly, Keaton had subsequently filmed a cameo in the upcoming Aquaman and The Lost Kingdom film, which is set to release December later this year, but of course, it is most likely that footage will ultimately be cut from the final version of the film. Although, the significance of the aforementioned footage has not been revealed to how it would affect the film.
Finally, the other Batman project that will not be seeing the light of day, was the cancelled live-action Batman Beyond film, in which, Keaton's Batman would have even more so been past his prime, and essentially seen him pass the mantle of Batman down to a much younger ally; perhaps a Robin he would have taken under his mentorship.
Ultimately it appears Keaton would have played quite a busy role as Bruce Wayne/Batman had Gunn and Safran never taken leadership, but seeing him return in The Flash, even if it was for the final time was surely a treat in it of itself.
Worlds collide when the Flash uses his superpowers to travel back in time to change the events of the past. However, when his attempt to save his family inadvertently alters the future, he becomes trapped in a reality in which General Zod has returned, threatening annihilation. With no other superheroes to turn to, the Flash looks to coax a very different Batman out of retirement and rescue an imprisoned Kryptonian -- albeit not the one he's looking for.
The Flash is a 2023 American superhero film based on the DC Comics superhero of the same name. Produced by DC Studios, Double Dream, and The Disco Factory, and distributed by Warner Bros. Pictures, it is the 13th installment in the DC Extended Universe (DCEU). The film is directed by Andy Muschietti from a screenplay by Christina Hodson and stars Ezra Miller as Barry Allen / The Flash alongside Sasha Calle, Michael Shannon, Ron Livingston, Maribel Verdú, Kiersey Clemons, Antje Traue, and Michael Keaton. In the film, Barry travels back in time to prevent his mother's death, which brings unintended consequences in the process.