*Warning: Major MCU spoilers ahead*
Time-travel related fan theories have been circulating about Avengers 4 ever since leaked set photos featuring the core cast in past locations from the Marvel Universe appeared online. In the photos, the Avengers team seems to be wearing wrist devices and are joined by Ant Man.
But why — and how — is Scott Lang (Paul Rudd) back with the Avengers? When last we saw him, he was stranded in the Quantum Realm, while his friends Hank Pym (Michael Douglas), Janet van Dyne (Michelle Pfeiffer), and Hope van Dyne (Evangeline Lilly) were turned into dust by Thanos. When he traveled to the Quantum Realm in the first Ant Man, Lang escaped using a Pym Particle, but director Peyton Reed has made it clear that will not be the case this time.