I am not a list kind of person. I have left things at home before, but nothing major and have always picked a new one up or just did without.

I presume this is an early or mid season hunt and not Montana in Nov right? For this time of year there really isn't much I'd not need besides the normal knife, binos, game bags, etc.

A pair of waders is one non-mainstream thing I always try to have with me, or at least in the vehicle.
A road flare makes instant fire in the middle of a downpour, though somewhat dry wood would still be needed to get a fire going for long. I don't mess with those girly matches.
I've also been throwing a light hatchet in my pack lately if the weather looks sporty.