A gallery of photos has appeared on Imgur that reportedly shows a movie theater that has been altered to serve as a set for Guardians of the Galaxy Vol. 2. The theater's marquee reads "Simon Williams Film Festival," and shows numerous posters featuring actor Nathan Fillion as Simon Williams - who, in comic books, is also the superhero/long-time Avenger Wonder Man - in a variety of films.
Fillion also cameoed in Guardians of the Galaxy as the voice of the unnamed blue alien that Rocket and Groot confront in prison.
The posters consist of homages to famous films, including what appears to be Tony Stark (a nod to Steve Jobs); The Toxic Janitor (a riff on The Toxic Avenger, whom Gunn directed a sequel to); Oh, Rebecca (a take on There's Something About Mary); Haxan 2 (a fake sequel to the silent film about witchcraft); and of course Arkon, a clear homage to Conan the Barbarian featuring Marvel's own inter-dimensional warrior Arkon, who most recently appeared in the Secret Wars tie-in Weirdworld. It's interesting to note that Conan was one of Marvel's top licensed properties in the '70's.
The breadth of these posters, which homage titles produced between 1981 and 2015 (or back to 1922, counting the original Haxan), seem to indicate that the film festival scene takes place on contemporary Earth, rather than in the past, before Peter Quill was taken by Yondu and the Ravagers in 1988. Gunn has previously stated that there would be "no Earthlings" other than Quill in GotG Vol. 2 - though if these posters are legitimately part of the film the door is open to that declaration being dubious.
According to ComicBook, the gallery was posted by Jonathan Hunter. The theater is located in Cartersville, GA, not far from Pinewood Studios, where Guardians of the Galaxy Vol. 2 is filming.
Guardians of the Galaxy Vol. 2 is scheduled for release May 5, 2017.