Earlier this month, images from the set of Avengers 4 in Atlanta, Georgia, were leaked online, showing actor Chris Evans' character Captain America wearing the original costume that he sported in Captain America: The First Avenger. This led to a speculation that the film would feature a time-travelling element.

Joe and Russo, who have kept quiet until now about plot details of the fourth Avengers film, have addressed this fan theory.

The directors hinted that the particular scene might have something to do with a certain technology shown in a previous Marvel film. "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," said Russo.

The technology he was referring to is Binary Augmented Retro-Framing (B.A.R.F.), which character Tony Stark (essayed by Robert Downey Jr) presents at MIT early into Captain America: Civil War.

In the scene, Stark shows visuals of the last time he saw his parents, Howard and Maria Stark, before they died on December 16, 1991.

Avengers 4 is slated to release in May next year 2019.