Even though there were early
Speaking with the magazine Film Ink, Snyder was emphatic that this universe and the Dark Knight trilogy do not occupy the same universe, saying, “This is a total and opposite reality from the Chris Nolan movies. It’s another universe, so we couldn’t hire Christian Bale [as Batman] if we wanted to, because he doesn’t exist in our world.”
However, Snyder considered having Bale show up as another character, just as a weird nod to the separateness of their worlds. He continued:
Maybe we could hire him to play another part. We did talk about that briefly. I just wanted to hire Christian to play another part to make that obvious. Christian could play, like, Alfred with age makeup. No! Of course not. But you know what I mean. Even people at the studio would say, ‘Who are you getting from the other movies?’ And I was like, ‘Hey, come on guys, let’s all understand, it’s a different world.’ In the Batman universe that Chris Nolan created, Superman would have a hard time existing. That that’s why we did a reboot on the universe, so we could allow these characters to exist together. We needed to do that to have Batman exist in this world.”
So, on the one side was the studio who wanted to create a linked universe with the Dark Knight and, on the other was Snyder saying it was a reboot. You know what? Snyder was completely correct in his assessment. Given the way The Dark Knight Rises ended, it would have been really strange to try to connect that to Man of Steel or Batman v Superman. Or even weirder to try to make Man of Steel take place simultaneously with one of the Nolan Batman movies.
Of course, having Christian Bale show up as a different character in Batman v Superman would have just been trolling. Can you imagine the crazy theories people would have generated just from his appearance on the set? Be so grateful this didn’t happen.