Trying to think of specifically what you could add to a pocket sized kit that would help in an urban situation, I can only come up with 4 things:

Small flashlight - always handy, even the coin cell type

Paper dust mask - handy if there are fires nearby or dust from fallen structures in the area.

Self adhesive retro-reflective tape - handy if you're walking near where others are driving. Even a 2"x4" piece front and back would make you much more visible to a car or truck at night.

Cash - a couple of 20's for rides and a couple of singles for vending machines, as others have mentioned.