According to reports, Sony's "The Amazing Spider-Man 2" contains a 'button' scene of footage, during the mid-credits, supporting the new Fox feature "X-Men: Days of Future Past", the first time Marvel Comics' characters 'Spidey' and the "X-Men" have linked up in the 'Marvel Cinematic Universe':
"...the scene features 'Mystique' (Jennifer Lawrence), 'Havok' (Lucas Till) and 'William Stryker' (Josh Helman) in a Vietnam camp during an action sequence..."
According to reports, the Sony/Fox Marvel placement deal was due to director Marc Webb having a previous contractual obligation to Fox. Fox released him to go make "The Amazing Spider-Man 2" and got a placement in return.
Click the images to enlarge and Sneak Peek 'Spidey' with the 'X-Men', "The Amazing Spider-Man 2" and "X-Men: Days Of Future Past"...