I found this to be rather entertaining and I remember when it was still in the process of storyboarding last year along with a couple of users doing the voice acting for Derpy and Doctor Whooves. Nice to see you did a lot of the animating and bringing it colorful life. Looking forward to seeing how part two will go and wondering if he will be able to master doing things with his hooves too since I imagine he will be in pony form for awhile until after he helps stops whatever event is meant to be stopped. Possibly the return of Nightmare Moon before she gets destroyed and frees Luna and turns her back into pony form.
The animation here went overly smooth although for a moment when Derpy scared the Doctor I thought the two red lines were him expressing surprise instead of the stems on the trees in the background. Also nice to see Derpy's eyes were moving the whole time and were perfect for a moment before going back to normal derp looking eyes. Then later on they decide to get a move on to get started on stopping the important bad thing that might happen.
The voice acting was just great here and nice to see Derpy keeping excited for the most part and also being confused at the same time as usual. Hilarious how she thought the bubbles meant her personality which could be true or debated as the Doctor said. Music that played in the back was also nice to hear. Something important got said then Derpy would be excited and music went back to playing. The credit sequence looked nice and cool how it was 8-bit.
Overall, excellent and funny at the same. Looking forward to the next part. Have fun helping with that one too.