The revelation is that Season 3 took place entirely inside Twlight's head after she looked into Sombra's evil door. Eventually, it started to run out of ideas, so it just made up whatever crazy stuff came to its head (see: Twicorn). The film is where it finally goes for broke, and the whole thing just becomes so absurd that Twilight finally breaks free. The final scene is the ACTUAL ending to the season premier, and a few months later we'll get our Season 3.1.

When prom is a plot point at all, I'm going to need a Nemesis invasion to salvage it.