4. Too Many Villains
The inevitable battle between the two heroes is more than enough to carry a movie, so it's a concern that the inclusion of villains from each of their rogues galleries could make this film feel very crammed - especially when some time will have to be spent introducing Batman again. Lex Luthor was hinted at throughout Man of Steel and, while no Batman villains have been confirmed, the likelihood of one of them appearing is pretty high. It's likely that Superman will first encounter Batman while the caped crusader is out on a mission, investigating a villain, but we should hope that there isn't an over-emphasis on whoever he is seeking out. The Avengers is a good example of how to accommodate numerous big characters in one superhero movie, but all of those characters were already established. Spider-Man 3 is an example of how introducing too many new ones can feel rushed, crammed and underdeveloped. We need to hope that this movie doesn't make the same mistake as the latter example.