Since Ant-Man and the Wasp was released after Avengers: Infinity War, but largely takes place chronologically before the events of the major MCU shakeup, fans were very curious what sort of movie they were going to get. However, in the end, they got a post-credits scene which caught everything up that saw several characters from the film fall victim to the Thanos snap. People were shocked at the way the characters were taken out, and it turns out so was the cast. Evangeline Lilly admits that even when they filmed the scene, nobody really knoew what was going on. According to Lilly...
It was on the day, we got called in for a scene, we didn't know really what the scene was going to be. We kind of had the rough shape of it -- outside, van, Quantum tunnel -- and that was kind of what we knew, and then we showed up and they handed us these pages and we were like, 'OK, so then what is this thing at the end? What's happening? I don't really understand.'
While everybody was informed that the scene would tie into Avengers: Infinity War, it seems nobody was told exactly how. In fact, Evangeline Lilly admits she played the scene entirely wrong, viewing it as a sort of "heavenly ascent" moment, rather than a "disintegrating into dust" moment. You can tell Marvel is trying to keep things quiet when nobody is even telling the actors what expressions they should have on their face. The actress just did the best she could with it while having essentially zero information.
Evangeline Lilly tells ET it wasn't until she actually saw Avengers: Infinity War that she understood how the Ant-Man and the Wasp scene related and that she'd played it entirely wrong. Of course, in the version that was put in the movie, we never actually see Hope, Janet, or Hank actually disintegrate. We just cut away from Ant-Man in the Quantum Realm to discover that the three of them are already gone.
The moment is a pretty strong punch in the gut to the audience who spends two hours having a good time and laughing at all the events of Ant-Man and the Wasp, then sees three major characters wiped from existence. It basically only leaves Ant-Man left to have any major impact on Avengers 4, and that's only if he doesn't spend the entire movie swimming through the Quantum Realm.
The fate of the Wasp is tied to the fates of half the galaxy. While most fans have an expectation that she and everybody else will return one way or another, that's far from a guarantee. Still, we only just got to see the Wasp kick ass and most of us would certainly like to see more of that. You can relieve the part we have with Ant-Man and the Wasp now out on Digital and Blu-ray.