imdb has the language down as Italian
But they could be wrong, or maybe (Like Bavas Twitch of the Death Nerve/Bay of Blood) they filmed scences in Italian and again in English?

Or the dubbing is just spot on
I've seeen some dubbed films were it can be hard to tell it's being dubbed

It seems this is the case. I watched several scenes, and sometimes the actors clearly are speaking English. Sometimes it's quite obvious they are not.

Btw: release thread here.