Variety and Just Jared have released pictures from the film's production Atlanta. Downey, Benedict Cumberbatch (Doctor Strange), Mark Ruffalo (the Hulk), and Benedict Wong (Wong) can be seen filming what appears to be the aftermath of some battle.
What's interesting is that Downey is sporting a new Arc Reactor in his chest. Tony Stark removed the reactor from his chest at the end of "Iron Man 3" and engineered a way for his suits to work without it in "Captain America: Civil War."
Fans have speculated that Iron Man receives a new injury that forces him to use a new Arc Reactor (perhaps this happens in the upcoming "Spider-Man: Homecoming"). A crazier theory is that he gets his hands on the Space Stone.
"Avengers: Infinity War" opens in theaters May 4, 2018.