B.A.R.F. also appears to tie in to a gallery of leaked set photos from the dual Avengers productions. The leaked photos appear to show Stark wandering through a memory from when Loki was captured after the events of The Avengers. When the photos were first leaked, it seemed only natural that these events were the result of Stark experimenting with B.A.R.F., but viewing these leaked images with a fresh set of eyes reveals a subtlety that was not apparent without first having seen Infinity War.
Thus, the time travel theory. But how does that work?
The first clue comes in the form of Tony Stark’s clothing. The scene depicted in the leaked set photos shows Stark wearing a uniform similar to the one the guard in charge of escorting Loki wears. If this scene is Tony revisiting the past through an augmented reality array, then why is he undercover? If he is viewing a moment from when he was fresh from the fight with Loki and the Chitauri, then he would almost certainly be wearing his gunked-up Iron Man armor. If this is months after, there’s no doubt he would be dressed, well, in a way that only Tony Stark could dress — to the nines and with ample swagger. There is no reason for Stark to remain discrete unless he is revisiting this moment in time in-person.
That sentiment is compounded by the fact that another photo appears to show Loki, still bound, holding the Tesseract, the housing unit for the Space Stone that allowed the Chitauri to wreak havoc on New York City. There is no conceivable way Stark or any of the other Avengers would allow the God of Mischief to gets his hands on the Space Stone so soon after he attempted to conquer Earth.
The only thing that would really make sense is if Stark were to go back in time and try to prevent Thanos’ invasion from happening, recruiting friends and foes to his side so they could strike the Mad Titan before that fateful snap. Whether that is the result of a heavily augmented B.A.R.F. or the Time Stone reclaimed (or something completely different) is a matter for the future.