"Captain America: Civil War" co-director Anthony Russo appeared at Comic-Con Experience in SÃ£o Paulo, Brazil, where he opened up about how Spider-Man made his way into the film regardless of who held the character's film rights (via ComicBookMovie.com).
"From the second we had the idea to do the story of 'Civil War,' Spider-Man was a part of the story," he explained. "It was a very complicated business arrangement for Marvel Studios to be able to use Spider-Man from Sony. So, we were always told by Marvel, 'Don't count on it, you may not get to use Spider-Man, so you better have a plan B.' And we were like, 'Okay, we get it, we have a plan B if don't get Spider-Man; we'll figure the movie out.' But the truth is, we never had a plan B. We only have envisioned the movie with Spider-Man. He was always a part of the story. It was very important to us to reintroduce the character."
Spider-Man's film rights were held solely by Sony for many years, until Marvel Studios struck a deal with them in February; this new deal allows the two studios to share the rights, so that Spider-Man may appear in Marvel Cinematic Universe films and vice versa. Spider-Man will make his MCU debut in "Civil War."