So, besides the above (good choices, and smart move on the iron filling!), I personally would add the following:
A few candles (either tea lights or a small, 1 hr stick)
Spare, small "focus" items (whether it's an actual focus item or not; sometimes, it's all the mentality, and it may have another use!)
Candy/cereal/protein bar (for yourself or to use as an offering)
Play-doh
I should also note that the items of a bug-out bag, at least in the magickal sense, will vary from practitioner to practitioner. In the local Pagan community, we all have our different practices, so we all have our own materials to bring to a ritual or in a "just in case" scenario (and some of us have "bug out bags" ready to go at home or in our cars). What I have in my personal bag is not the same as my friend's. For example, in my "just in case bag," I have a bag of sea salt, some ashes, a charm purchased at a Shinto shrine during a stay overseas, a chunk of quartz, some tea lights and the aforementioned cereal bar. My friend has a belief that's a bit closer to the Native Americans, so he carries a few feathers (of birds of importance to him), a small shell, a turtle vertebrae, something from a buffalo, tobacco, and sage in his "just in case" bag.
Long story short, really depends on the caster, because in the Dresdenverse, what Harry would carry in his bag/on his person (which probably would consist of play-doh, salt/sand, chalk, matches, candles, some coins, chocolate bar, a drink, holy water, etc) is going to be different from Elaine and Injun Joe Listens-To-Wind because their approaches and belief in magic will be different.
Just tossing it out there, hope it all helps ^^;