I notice some of the default sounds have noticeable clicks at the end of them that probably weren't supposed to be there but ended up there anyway. I've got edited versions of chain, electric, and thunk attached here that just have those last few bytes at the end removed. To be fair, the clicks at the ends of chain and electric aren't that bad, but the one at the end of thunk most definitely is.
Also, I'd like to add that I think fire is significantly too loud. I find it pretty loud on its own myself, but that might just be me, but the bigger problem is that a lot of instances of the sound can play right on top of each other, and the sound is not that short, so multiple lemmings getting burned within frames of each other can get overwhelmingly loud real fast. Maybe it is just me since I haven't seen anyone else mention it, but still.