The latest word on the grapevine is that Christian Bale, not George Clooney, was supposed to appear as Bruce Wayne, also known as The Batman, at the end of The Flash.

But, while many have picked up this rumor and believed that it's the truth, especially since it supposedly comes from Kevin Smith, the truth isn't as it seems.
Apparently, the reports are based on a portion of what Smith said, which he himself confirmed on Twitter.
What’s missing from this Fat Man Beyond clip is when I said “I think there’s a world” and “It feels like”.
It was just conjecture,
not inside information.
Here’s an actually credible @THR article by @Borys_Kit about how that cameo was shot 6 months ago: https://t.co/Ox72UJ6LXJ https://t.co/yYFX9l01Gf— KevinSmith (@ThatKevinSmith) June 25, 2023
The Flash, whose story charts a twisty path through a convoluted timeline that isn't unlike its tumultuous production, lands Barry Allen in a reality where Ben Affleck's Batman is replaced, initially, by Michael Keaton's, and eventually, a universe that sees George Clooney is the eccentric billionaire who likes to dress up as a bat at night.
During The Flash's final act, a key decision is made by the fastest man alive. He resolves to let the past take place, allowing the tragic murder of his mother to stand, thereby restoring his timeline. But, as a parting gift, he manages to exonerate his father, who was wrongfully accused of the crime. This decision, seemingly minute in the grand scheme of his time-altering exploits, creates a ripple effect. That ripple swaps Affleck's Batman for Clooney's, an unexpected turn that was not the initial concept.
In the original drafts, the filmmakers had sought to replace Affleck's Batman with the one portrayed by Michael Keaton, an iteration adored by the fandom. However, behind the scenes, an even more thrilling prospect was initially pursued.
Many reports claim that Warner Bros. had spent several months attempting to convince Christian Bale to reprise his role as Bruce Wayne from The Dark Knight Trilogy. This casting would have been an incredible coup for DC, with the trilogy, which is helmed by Christopher Nolan, both fresher in the minds of the audience and a subject of immense affection.
Bale, however, remained steadfast in his refusal, expressing his decision to not play Batman again unless Nolan was at the helm, as per the reports.
Bale's association with the character of Batman, which he brought to life in Batman Begins, The Dark Knight, and The Dark Knight Rises, holds a special place in the collective consciousness of the superhero fandom. The actor's portrayal, nuanced and intensely human, set a new standard for the representation of Batman on the big screen.
To fans, Bale's Batman is more than a vigilante in a cape and cowl; he's a beacon of perseverance and grit, a symbol of resilience - something that one of his successors, Robert Pattinson, can only hope to achieve.
Bale's steadfast refusal to reprise the role of Batman without Nolan only underscores the deep respect and admiration he holds for the director, whose visionary storytelling made the trilogy what it was. Nolan's intricate narratives, striking visuals, and masterful direction elevated the superhero genre, and his collaborations with Bale resulted in a portrayal of Batman that has left an indelible mark on popular culture.
Of course, this isn't exactly true, as Bale, as far as Kevin Smith is aware, wasn't approached nor planned to cameo in The Flash, despite the insistence of several rumor mongers.
At the end of the day, all of this speculation is rendered moot when The Flash likely isn't getting a sequel that would've introduced the Reverse Flash due to its lackluster box office numbers. We highly doubt Bale's inclusion, especially at the end, would've changed that.
Going forward, the DC Universe has massive plans for the Dark Knight, with Pattinson reprising his role as Batman in The Batman - II. On the other hand, Andrés Muschietti will link up with James Gunn to direct The Brave and The Bold, which is presumed to premiere after Gunn's Superman Legacy comes out in 2025.
It's unclear if Gunn is open to revisiting the multiverse concept in the future, but the ending of The Flash leaves the door open for such shenanigans.
Who knows? When that happens, Bale might be more lax with his Nolan-only requirement and be more willing to literally don the cape and cowl once more. After all, who would've thought that after three decades, Michael Keaton would return as Bruce Wayne on the big screen?