Following the initial release of Man of Steel, there was talk of doing another Superman movie, which didn't include Batman.

Obviously, that didn't happen, but now a new detail is learned about Man of Steel 2 that references the Dark Knight.

In the Batman v Superman: Dawn of Justice Art of the Film book, Zack Snyder reveals an ending discussed for Man of Steel 2.

"Originally, it was going to be a straight Superman movie," Snyder explained. "One of the ideas was that at the end of the movie, a crate of kryptonite would be delivered to Wayne Manor. That didn't happen, but once Batman was mentioned, he wouldn't go away. It couldn't be undone."

Other details we know about the what-could-have-been Man of Steel 2 movie is that it featured an older Lex Luthor. Zack Snyder recently revealed they spoke with Bryan Cranston for the role, and Snyder told Total Film magazine a while back they had to tweak the Batman Vs. Superman script to accommodate using a younger 32-year-old Jesse Eisenberg.

“We talked about the usual suspects that you would imagine; any actor who has been bald, probably,” Snyder previously told Entertainment Weekly. “Bryan Cranston would have been great, right? And by the way, he’s an amazing actor. Can you imagine how different the movie would be?”

The Batman v Superman: Dawn of Justice art book also reveals that Chris Terrio wrote (or rewrote from David Goyer's script) scenes involving Laurence Fishburne's Perry White, another Superman character.

"Chris Terrio has done such a great job of continuing what we've established with Perry White, but just turning him up a notch," co-producer Curt Kaneomoto offered. "It's really, really fun to see how he takes these gentle and not so gentle stabs at Clark in the film."

The book even mentions the neon LexCorp sign seen in Batman Vs. Superman belonged to Lex's father, and that Lex featured the sign in the lobby as a trophy over his victory of taking the company from his father, among their troubled relationship.

"Zack wanted Patrick [Tatopoulos] to come up with this gigantic old neon sign that maybe belonged to Lex's father," Batman Vs. Superman art director Gregory S. Hooper said. "It was on a rooftop. So, our graphic artist designed an enormous sign. I went down to Cleveland and had that built and installed, and it looked amazing."

Details are also mentioned that under Lex Sr., LexCorp was more focused on Wall Street or The Big Three automakers. When Lex Jr. came on board, Lex Corp was then modeled on Silicon Valley.

The various details for Man of Steel 2 that we can put together are rather interesting as:

• Obviously Man of Steel 2 would have solely focused on Henry Cavill's Superman/Clark Kent.

• Would not have featured Batman (or any other Justice League characters most likely).

• Would have featured an older Lex Luthor.

• Would have featured Kryptonite.

• The ending would have seen a crate of kryptonite delivered to Wayne Manor, which we can speculate:

• Batman would have obviously taken notice of whatever happened in the movie and had the crate delivered to himself.

Or

• Lex Luthor Sr. delivered the kryptonite crate to Bruce Wayne (which is similar to what happened in Batman Vs. Superman), and this also would have revealed Lex Sr. knew about Bruce being Batman (and possibly other metahumans, again similar to BvS).

There were also rumors following Man of Steel that WB was going to do a solo Batman movie (possibly with a younger Bruce Wayne). It's possible we could have had Man of Steel 2, a new solo Batman movie, possibly Batman vs. Superman or Batman AND Superman, then Justice League.

Or, for that matter, following Man of Steel 2 and a standalone Batman movie, right to Justice League.

Going the Man of Steel 2 route seems as if the Justice League universe may have been built up more slowly (compared to the Batman Vs. Superman cameos), and that Superman would have been the lead.