Thanks ! I totally see what issue you are talking about and it has to do with the way I coded the interaction between Blues and the boxes, he needs to have speed when he collide with the box in order to push it, so that's why when you're stopped by Pinkye you become unable to push the box before first taking a few step back to be able to build speed. I know it really isn't perfect but I didn't find any better solution.
As for particle effects and lighting, I totally agree, I just didn't get the time.