I really don't know what else to make of this. On the back of the clone trooper (This is a downloaded model by Syth, actually), a thorn-like shape will pop out while the clone reloads his rifle. It's probably the animation, but I don't know, I can't get rid of it, and I need advice.

It looks like the envelope weighting and there's nothing you can do about it unless you reverse engineer it and re-export it.
Where exactly did you find this buggy version? (link please)

It's Syth's ep3trooper. It, along with several other files, were found here. Also, the exact same problem occurs with the Helmetless-clone model. Do you want that link, too?

I'm gonna be honest with you: I am no good with doing anything with models except hex-editing. Everything else is easy as pie.

well this problem can only be "fixed" with XSI reenveloping and the pandemic tool, not with hexediting
(or did any hexediting-wizard find find a way that i missed?)