Spare pair of sock's, toothbrush & toothpaste and toilet paper.
It's the little things that count after a night out in the rough. Traveling light is good but I would put a small tin with a couple of MP-1 tablets, a small plastic bag (for water), tinder, button compass and a lighter in one of my trouser pockets. Weighs nothing and improves your chances 100%. I like to think of it as my hollow handled knife kit......