Having read the original comic storyline Civil War, and all the additional titles brought in to fully show the breadth of Tony Stark's decision to force superhero registration, I was a little disappointed with the MCU film, but understood why they had so few heroes involved, as to truly show how widespread the rebellion became against Stark.S.H.E.I.L.D, the budget for adding all the heroes and villains would have bankrupted the entire film industry, but would have been FAR more spectacular (And much, much longer, too :->). Even using CGI to include the characters would have taken an immense effort.
Having read the original comic storyline Civil War, and all the additional titles brought in to fully show the breadth of Tony Stark's decision to force superhero registration, I was a little disappointed with the MCU film, but understood why they had so few heroes involved, as to truly show how widespread the rebellion became against Stark.S.H.E.I.L.D, the budget for adding all the heroes and villains would have bankrupted the entire film industry, but would have been FAR more spectacular (And much, much longer, too :->). Even using CGI to include the characters would have taken an immense effort.