it's clearly left intentionally vague and you're not supposed to walk away with a clear answer of what was real or not. It could've all been in his head due to some schizo/psychotic break, or perhaps even be a mix of things that actually happened coupled with hallucinations. It's not a stretch to say he actually stabbed that homeless man because of how tame it is compared to everything else, but the ATM asking him to feed it a cat is very clearly imagined, and it only leads to further questioning of what could be real or hallucinated. It's not clear. I don't believe he'd be able to get away with dropping a chainsaw on a bitch's head, too much commotion.