Avengers: Infinity War promises to transform the Marvel Cinematic Universe in ways that fans can only guess at, but it's been the production of Avengers 4 that has raised even bigger questions. In recent months, we've seen more and more set photos that seem to indicate that parts of Avengers 4 will be set in the past, possibly as part of a time-travel storyline that provides a fix to the Infinity Gauntlet threat.

Well, in a recent interview with MTV's Josh Horowitz on his Happy Sad Confused podcast, Avengers 3 & 4 directors The Russo Bros. addressed the rumors swirling about Avengers 4's possible time-travel antics. Here's what they had to say when Horowitz not-so-slyly asked how they feel about time travel as a plot device in film:

Anthony Russo: "Oh you know, big fan of the technique."

Joe Russo: "Back to the Future..."

Anthony Russo: "Yeah, Back to the Future..."

Joe Russo: "Look, it's interesting because yes there are photos that always leak, and then there's lots of conjecture about what those photos mean. Certainly there is a five-minute sequence in 'Civil War' around a piece of technology that was laid in for a very specific reason. So if you go back and look at that film, you may get a hint as to a direction."

That cryptic tease is of course reference to the Binary Augmented Retro-Framing technology that Tony Stark unveiled in Captain America: Civil War. If you don't remember, it's the memory projection system that Tony uses to replay the last time he saw his parents for a crowded room, as a method of treating psychological trauma. The sequence was especially memorable, because it featured Robert Downey Dr. "de-aged" into his younger self through CGI.

The "BARF" technology from Civil War was just spotted on the set of Avengers 4, which definitely sets up a case for the film revisiting the past in some form or fashion. Whether that's actual time travel, or trying to comb through the memories of a very important figure, is up for fans to debate. There are a fair number of them who would love to see Avengers 4 reboot the timeline of the MCU, in a way that helps bring in Fox's X-Men and Fantastic Four franchises. However, if some theories about Inifnity War character deaths are right, then Tony Stark may be so badly hurt in Avenger 4 that his BARF tech is the only way to reach him.

Avengers: Infinity War opens in theaters on May 4, 2018. Other upcoming Marvel Cinematic Universe movies include Black Panther on February 16, 2018, Ant-Manand the Wasp on July 6, 2018, Captain Marvel on March 8, 2019, the fourth Avengers movie on May 3, 2019, the sequel to Spider-Man: Homecoming on July 5, 2019, and Guardians of the Galaxy Vol. 3 in 2020.

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