But this shot, from the set of The Amazing Spider-Man 2 shows what looks to be subway tracks, with the closest thing we have to webshooters being a little bit of cobweb between the wood.
The caption says "Mar 83," which might be a clue of some kind. The March, 1983 issues of The Amazing Spider-Man and Peter Parker, The Spectacular Spider-Man featured The Hobgoblin and The Black Cat, respectively. Both of those characters have been speculated to be involved in the Marc Webb-directed sequel but no credible report has emerged to indicate that either character has been cast.
That said, the March 1983 issue of The Amazing Spider-Man, which introduced Hobgoblin, is widely considered as one of the best stand-alone stories of the '80s.
Fans don't seem to have had any input into the image, either; while Webb's tweets generally elicit predictions as to what they might mean, nobody has responded to this image yet.