Got to be honest...
I adore this series, and was thrilled to finally see part 4 posted here on Newgrounds. The quality of the animation, music, and voices were phenomenal as usual. The one problem with this installment of the series, was that it was obviously rushed, as you mentioned, and it kind of seemed that way throughout more than just the ending scenes. :( Maybe it's just me, but it seemed like there was something missing that could have been added in to make things flow a little better.
Anyway, I would love to see this re-uploaded one day with the final boss battle added in, and I'll still be looking forward to part 5 when you get around to completing it. Keep this series going, it's still one of the best on Newgrounds.