Great first episode! It's really neat to see a series like this, in which I mean sprites and Sonic related content, being featured in NG. I thought those times were long gone.
Anyway, the animation is simply superb! You make use of sprites like no other I have ever seen, and I really mean it! Of course it does not have battle scenes that everyone loves and brags about, but in this case who cares! I got engaged in the story telling and in the beautiful use of sprites here. As an animator of the sort myself I can assume you expended a good deal of time in this little movie.
One thing off in my opinion though was the voice acting. Sonic's voice was ok. But Robotnik's one was a little off. I mean, we spend a good chunk of the movie listening to him, and sometimes it does not seem like him at all. Also, Tails' VA seemed like trying to be sound like a kid while being a mature man lol
Another thing was the lack of a scene selection. You might want to take that into consideration next time, even if the movie is as short as this.
Overall, keep up the good work! And I'll definitely look forward to you next movie.