10. It's Not About Secret Identities
In the Civil War comic book, the Superhuman Registration Act divided the world's heroes because so many of them were unwilling to reveal their identities to the government (mostly in fear of what would happen if that information were to go public and the ramifications such a thing would have in regards to the safety of their families).
In the film, however, it's the fact that signing up means they'd have to work for the government, only a sub-plot in the comics.
That's because no one in the Marvel Cinematic Universe really has a secret identity, something Kevin Feige acknowledged in an interview last year when he said that the "generalities of the act are the same" and "it’s not about the secret identity thing, as much as it is about, overall, who reports to who, and who can agree to oversight committee."
It's clear then that this movie will be a culmination of everything that's come before, with some heroes happy to be called into action when the government sees fit, and others unwilling to be used as pawns (no doubt in part because HYDRA's infiltration of S.H.I.E.L.D. proved it's hard to know who to trust).