Not a bad collaboration, i dont see why some people are complaining so much. It's obvious you guys got talent and there's always gonna be things that need improvement. Voice acting was a bit forced, but I didn't find it annoying so people stop complaining already.
Personally I didn't see much problems with it, and I thoroughly enjoyed the display of different animation styles, although some things didn't flow well...like the 3-D sequence where the villagers were using guns whereas the in the other sequences everyone else was using bows, arrows and swords and other tools....try to keep it consistent. Also some of the blood spills were poorly animated in some instances, i don't think that blood flows out in flashes if you know what I mean. Also didn't see much action from the purple guy, try to balance the seen action from the main individuals out a bit.
Otherwise nice collab! Just remember where you slipped up and you'll be fine. Stuff like this is always a learning process and you're doing fine anyway. :)