3. Governmental Mistrust
Whether or not the current Justice League script references Project Cadmus directly or not, Id still love to see a governmental mistrust of the Justice League factor somewhere into the film. Because unlike in The Avengers, the Justice League arent called into service by a government agency like S.H.I.E.L.D; they start themselves up when they have the realisation that some threats are too great for just one Leaguer, even Superman. Can you imagine if a team of super-powered beings (and Batman) formed by their own volition in reality? How freaked out the various World governments would actually be? This is where I think the Justice League movie could take a right turn from what made The Avengers so successful, in the pursuit of originality you understand. Im not saying that we should see Earth vs. The Justice League, but lets have some governmental mistrust acting as a potential reason for the Justice League to simply not bother; only to have them save the day anyway, because they strive for Justice (clues in the name) and not simply to appease the government.