Spider-Man and Black Panther

At this moment, these are the greatest secrets of the MCU's Civil War "“ we don't know what their roles will be in the movie. Sure enough, based on the comic book characters, we may believe that Spider-Man will eventually join Iron Man and we may believe that Black Panther (given the seclusion of his home country) will have an agenda of his own.

So, in a way, we aren't even talking about unmasking them "“ Black Panther will certainly not do that for the public of the whole world, while the unmasking of Spider-Man (just like in the comics) has no reason to happen, as said at the bullet above.

Avengers after Age of Ultron

Animosities between the superheroes were noticed from the first Avengers film and became even more visible during Age of Ultron. Given the number of superheroes that will be present, it can be said that Civil War might just be the second part of Age of Ultron.

As of this moment, IMDB lists no less than 11 major players (without Spider-Man), leaving the villains aside. And that is a huge number by any standard, if we are considering the MCU. Sure enough, there are no X-Men or Fantastic Four in this Civil War, but still "“ this cast dwarves the one of the first Avengers film and is bigger than the one of Age of Ultron.