While Ash is trying to get out of the pit with the Deadites in it (VERY beginning), he takes his belt off so the holes are in his hand. When he uses it like a whip, the holed end wraps around the chain. How'd he do that?
This is one of the things that makes this movie so funny. There's pretty much no possible way that could've happened! Just like the big blood spurt from out of the pit. How could that have happened? It couldn't have! Its so tongue-in-cheek, and it's great!
Yeah, I see your point...it's not possible to use your belt like a whip...but it IS possible to attach a chainsaw on your hand, go back in time, meet an evil twin of yourself, and fight off an army of skeletons and zombies? My point is this...it's SUPPOSED to be that way...it's fiction, not fact.