The working title (Batman vs Superman) is not mentioned so we should be clear on that immediately. We think its clear as glass as to what movie has recently pulled out a casting call on the Michigan Film Office website
This Warner Brothers call has asked for suits, military, and law enforcement types all over 18 years and can be either male or female. Rewind back to Man of Steel and Superman had his hands full fighting General Zod who was destroying Earth with a host of “military types” playing key roles throughout the film.
With Lex Luthor being cast in the sequel you could imagine the requirement to have a host of “suits” throughout the film also
You can’t miss the request in the advertisement that says, “NO COSTUMES PLEASE”. If people catch onto what they are applying for (as an extra) the production company wouldn’t want a host of fans showing up in superhero costumes. Wouldn’t be ideal for anyone. Also note that the advertisement has asked applicants to be free to work in Detroit between June and November of 2014. It could possibly tell us how long the filming for Batman vs Superman will take in Michigan.
Source: comicbook.com