Two things:
1. Usually different types of sprites and backgrounds (eg. 8-bit/16-bit/GBA-style sprites/backgrounds) don't really clash up together. It looks weird. Try to keep it 8-bit with 8-bit, GBA-style with GBA-style, and so on.
2. You could try and do the motion blur way better. Lines look too unprofessional. If you're using Paint.NET, then
this could work.Other than that, it's pretty good, even though the humor is kind of simple sometimes.