Woodchipper scene
The Woodchipper scene really underlines how unstable these people are.
Putting a person in a woodchipper serves absolutely no practical purpose. It's hard to do a more loud and high visible disposal of a body and it won't even prevent them from identifying the victim. On top of that a normal person would probably want to avoid something as grizzly as that, but again, the whole point is that he isn't.
He would've been better served wrapping up the bodies and burying them in the forest out back. It would take time for them to find them. If there's a woodchipper there's most likely other tools he can use to dig in the hard soil as well.