Let me start by saying nice job.
You've created characters and a story that can continue into a series.
You've also done a decent job with animation and created a situation where the alien can do many things because he has cool alien devices. You've done a lot here! So it's hard to pick it apart since so many others submit crap... but here is what I see.
The sound is good. Good voice acting. I think it could use a little more humor or adventure to it...
The animation is good... but you just need to add some more visual "pop" to it. For example. When bunny grabs the alien and runs... he's in a straight up vertical position and his legs are kind of flailing along... lean him forward or backward... have his ears flying back and flapping in the wind... have the alien flowing at more of an angle... you know... give it a REAL action feel! Also I would move the background a bit faster behind them or make a blurry background to give the impression of more speed...
Overall you have made a very good effort... and I admire that you are doing something productive and trying to make an entertaining series!
Keep working on it... I'll keep watching!