Ant-Man may have been in the Avengers: Endgame trailer more than you thought. Ever since Scott Lang survived Thanos' snap in the Quantum Realm in Ant-Man and the Wasp's mid-credits scene, it's been clear that the shrinking hero will be an essential part of Avengers 4. This was hammered home when the much-anticipated first trailer for Avengers: Endgame closed on him arriving at Avengers HQ, much to the surprise of Captain America.
The post-title stinger showed Scott turning up with the Quantum Tunnel van, shouting at a security camera to be let in. What wasn't made clear was when he was arriving; Black Widow confirmed it was the front door, but Steve Rogers was unsure if it was live. This has led to much speculation of time travel - it's been posited the Scott recording is from both the 1980s and direct aftermath of Thanos' decimation - although what's unavoidable is that the Avengers thought Ant-Man was lost; Scott appeared as one of the "missing" alongside Peter Parker (who turned to dust unreported on Titan) and Shuri. But is there more to it than that?
A key part of the Endgame trailer is Black Widow explaining the end of Avengers: Infinity War - Thanos succeeded in wiping out half of the universe - with Bruce Banner looking at a slideshow of the dead. However, neither aspect is as it seems. Black Widow's speech comes over a shot of Captain America, who already knows what's happened, while Banner is looking at the back of the missing holograms; there appears to be a mystery person off camera having the situation explained to him. And who's a better contender than Ant-Man?
A strong theory is that, typical of Marvel marketing, the Avengers: Endgame trailer is completely out of order and its end is actually the beginning; it would make sense for the film to kick off with Ant-Man escaping the Quantum Realm (likely via the help of time vortexes), then his arrival at Avengers HQ serving as both his and the audience's introduction to what's really happened to the world in his absence. In fact, there's really no other character who would fit better as an audience surrogate to have the information relayed to, and it would provide a direct narrative drive to every shot of saddened heroes in the trailer.
Of course, all of this speculation distracts from a much bigger point in the context of Avengers: Endgame: all of this happens very early on in the movie. It's been suggested by fans that the trailer doesn't show much beyond Avengers 4's first twenty minutes, and if Ant-Man arriving is the catalyst for recapping the previous movie, that would appear all the truer. The only parts that possibly come later are the reveal of Hawkeye as Ronin, which obviously sees Black Widow travel from upstate New York to Japan. Still, this shouldn't be too surprising; with an expectation that the movie will involve a massive time travel mission to somehow avert Thanos' snap and a myriad of casting rumors, any setup will have to be quick - and a short Ant-Man scene is just what's needed.
Based on Avengers: Infinity War's marketing campaign, a second look at Avengers: Endgame - albeit a shorter TV spot rather than a proper teaser - will likely arrive during the Super Bowl, with a full trailer ahead of Captain Marvel in March. By this time, we should have a much better idea of what the MCU culmination is about - and how Ant-Man fits into it all.