Updated August 27, 2015 at 5:34 p.m. EST: Shortly after this artwork appeared online, Hawkeye himself Jeremy Renner circulated the artwork on his social media accounts and even commented on it positively. While that's not an official confirmation, it is a strong indication Renner (who would presumably have insight) believes or knows the artwork is legitimate.
Original Story: Images purported to be concept art from Captain America: Civil War have surfaced online. While their authenticity remains tacitly unverified, the images show what could be Captain America and Iron Man's factions for the film.
While most of the line-ups shown in the supposed concept art are fairly expected, there are a few surprises, such as the lack of Spider-Man on either side, and the presence of Sharon Carter on Cap's team. Still, for the most part, the line-ups correspond to recent rumors, and to what we've already seen verified by some of the actors.
The images were revealed in a video from a YouTube user known as "Mr. Sunday Movies," seen here.
Captain America: Civil War hits theaters on May 6, 2016.