Not every actor who plays a superhero in the Marvel Cinematic Universe has admitted that they’ll be among Avengers: Infinity War’s 68 characters, but enough have that we can assume everyone who has ever punched a Hydra goon or killed a Chitauri invader—unless they’re from Agents Of S.H.I.E.L.D. or the Netflix shows—will make an appearance. That still leaves the door open for surprises, though, like the mystery character Peter Dinklage might play or the new reveal from Karen Gillan that her Guardians Of The Galaxy character will “be making a little appearance” in Infinity War.
That quote comes from a BBC profile (via /Film) in which she briefly talks about her upcoming projects, and though she doesn’t offer any details beyond that, it may be an important detail that connects Infinity War to the comic book miniseries that it’s (probably) based on, Jim Starlin, George Pérez, and Ron Lim’s The Infinity Gauntlet. The big background story in the MCU has been Thanos very gradually collecting the Infinity Stones—a.k.a. the MacGuffins that most MCU movies revolve around—and the Infinity Gauntlet story is all about what happens when he possesses them all and becomes the most powerful being in the universe. Nebula, the character Gillan plays in the Guardians Of The Galaxy movies, is there the whole time so she can bear witness to Thanos’ ultimate victory.
Now, the MCU movies rarely include direct adaptations of comic book storylines (as anyone who predicted Captain America would die at the end of Civil War can attest), but Nebula plays a very important role in the end of The Infinity Gauntlet. That means—perhaps even more so than any of the heroes—her involvement in Avengers: Infinity War could end up being a pretty big deal. It probably won’t, because Gillan said it’s only “a little appearance,” but it might.
We’ll know either way when Avengers: Infinity War opens on May 4, 2018.