Avengers: Endgame’s trailer has arrived already and has brought a wave of excitement with it. It also got back Scott Lang who was believed to be lost in the Quantum Realm after Ant-Man 2. His arrival and a small line at the end of the trailer may be the key to take down Thanos.
Lang shows up outside the Avengers complex and it’s clear that Captain America and others had already thought him disappeared after the “snap”. His face was seen in the list of those who went missing after the snap, and we can see Cap questioning if the footage of Lang at the door is an old one.
The truth is that Scott Lang is the only member of Team Ant-Man to have survived the snap. He was inside the Quantum Realm when the snap took place while Hope Van Dyne, Hank Pym and Janet van Dyne all turned to dust. We all thought that without his team, he may have trouble in finding his way out of the realm.
But thanks to the trailer, we know that he will be back and looks fine, although it’s still unknown how he returned. The footage also shows Scott in front of a cab than Hope and Hank used to stay ahead of FBI after Sokovia Accords. The Quantum tunnel was in the back of that van and now it’s safe to assume that Avengers have access to the tech.
Photos from Endgame sets revealed the Avengers wearing some old costumes and even reenacting the battle of New York. Artwork suggests that Avengers will also suit up to visit the Quantum realm. Before Ant-Man, Janet had spent years in the realm and had warned him not to get stuck in a time vortex. This is a term that alters time and perhaps helped Lang to escape the realm.
Getting back from the realm, Scott may have realised that the key to undoing the damage brought upon by Thanos is time vortex itself. With this, Avengers may head into the Quantum realm and travel back in time to stop Thanos before he snaps his fingers.
There’s also the theory that the footage of Ant-Man at the Avengers complex is old footage. Either way, the moment seems to answer another question about the Quantum Realm left lingering after Ant-Man and the Wasp.