An actor spotted on the set of Avengers 4 may have finally proved a big theory about the upcoming movie is true

He is reported to have filmed his scenes with Robert Downey Jr.

Will we ever get tired of theorizing about Avengers 4 aka Infinity War 2 aka Whatever They End Up Calling It? Not any time soon, no. Just last week we reported that the arrival of the Skrulls in the upcoming Captain Marvel movie, and knowing that movie takes place about 20 years before the events of the Infinity War, fans are now convinced that we're about to find out that one of the Avengers has actually been a secret alien spy this entire time. As if that wasn't enough, this week it has been reported that... Oh, wait. SPOILERS. Okay, on we go. ... it has been reported (via Geek Tyrant) that Robert Downey Jr. was spotted on set filming scenes with John Slattery, who you'll remember played Howard Stark in Captain America: Civil War. While those scenes were achieved with Tony Stark's holographic technology that recreated moments from memory, these new scenes feature a present-day Tony interacting with a back-then Howard, which would indicate that time-travel is very much involved. We kind of always guesses that the Avengers would get round to nabbing back Doctor Strange's time stone to set right all the wrong that Thanos inflicted at the end of Infinity War, but Tony going this far back would indicate something much more. Back when Infinity War was first released, we theorized three potential outcomes for the sequel, and if Tony is going decades back in time, that it would appear our most outlandish ending might be about to prove correct: "There was a conversation had in Civil War, when Vision tells the group that ever since Tony Stark outed himself as Iron Man, the number of catastrophic events has climbed to match the number of Avengers joining the ranks. So there is a chance they'll click themselves so far back that it will undo everything that the Marvel Cinematic Universe has done so far, but it still allows room for several of the actors to bow out, as an alternative path sends the Avengers on a different journey altogether, with different members and different famous folks inside the different spandex suits. This would be the MOST BALLSY ending." Very ballsy indeed. Considering the movie is still being filmed, and some actors don't know if the outcome of their characters will remain the same in light of everything that is happening with James Gunn and Guardians Of The Galaxy 3 (more on that here), it could result in Slattery's scenes being cut and the movie going in a completely different direction altogether. We'll all know for sure when the currently Untitled Infinity War Sequel hits Irish cinemas on 26 April 2019.