Nope because its part of the act ! Or in other words a fake.  Its a good one to have you all fooled but take a look back and you will see a number of things that wouldnt add up if this was a real incident which prove the illusion was simply an illusion. Like why was there a partially covered head box in the first place ? Look again at the sequence the magician uses: He inserts a metal blade down through the neck before any saw is used, so logically if it had gone wrong  the blade should have killed the girl in the first place way before the chain saw even got a look in yet she was still waving her arm about. The chainsaw , fake blood and the rest of the playlet all there simply for maximum theatrical effect.

there no way that was fake

Magician Accidentally Kills Wife
wow is this real?