Just saw it and loved the movie
Spoiler: show
Interesting they went with Mushroom Hill which was technically designed for Sonic 3 before the game was split into two.
I have a feeling that Eggman ends up finding a Chaos Emerald in Mushroom Hill and starts jumping zones to collect more and invades Tails home which causes him to seek out sonic. Imagine if there was a buildup for finding the chaos emeralds...fans would blow their load seeing Super Sonic on screen...