Please read no further if you don't want to know any potential spoilers from the untitled fourth Avengers movie.
As speculation continues to swirl around the plot of Avengers 4 and just how Earth's Mightiest Heroes will undo the catastrophic "snap" by Thanos that sent untold trillions of living beings into nothingness across the universe, one player from the past has let it slip that he's showing up in the movie.
That player is actor Frank Grillo, who played the villainous Brock Rumlow, aka Crossbones, in Captain America: The Winter Soldier and Captain America: Civil War. Posing as a S.H.I.E.L.D. agent, Rumlow was eventually revealed as a HYDRA operative and, in Civil War, was bent on revenge against Captain America (Chris Evans) for the severe burns that left him disfigured at the end of The Winter Soldier.
Rumlow's plans were thwarted, and he ended up dying in an explosion at the beginning of Civil War, seemingly marking the end of that non-superpowered character's involvement in the MCU. According to Grillo, however, we have not seen the last of Crossbones.
Speaking on the UFC Unfiltered podcast, Grillo revealed this nugget: "[Crossbones] makes an appearance in the next Avengers movie, but it’s a flashback. And I’m allowed to say whatever I want because I’m never doing another Marvel movie." Asked why he won't be doing any more work for Marvel, Grillo jokes, "Because I’m 117 years old.”
Well, Grillo is actually only 53, but he must feel fairly certain that this is truly the end of the line for him in the MCU for him to casually let that little morsel of info fly.
If what he says is true, about Crossbones appearing in a flashback, then it's just another addition to the building body of evidence that suggests Avengers 4 will involve time travel. There are already photos out there on the interwebs of costumes and scenes from past movies (specifically Cap's gear and the Battle of New York from the first Avengers) being recreated for Avengers 4, and there have been strong suggestions that the Quantum Realm's time vortexes might be used as a gateway to the past. And let's not forget the Time Stone is still affixed to the Infinity Gauntlet and has been used once already to turn back the clock.
Will Cap or more of the surviving Avengers travel back in time to key moments in their history, in some kind of mind-bending effort to undo the damage that Thanos has done, or perhaps prevent it from ever happening? And what will that mean for the very existence of the Avengers themselves? We don't know that yet, but it seems more and more likely — from the hints provided by Grillo and others — that the Avengers will journey to the past in an effort to save the future.
Avengers 4 arrives in theaters May 3, 2019. Can we travel forward and see the darn thing already?