>>1320315atrocious.
Number one - if it ever comes to that, and you need to "bug out", chances are it's not a total WROL/Back to basics scenario, but you need to evacuate your immediate area, and get somwhere safe.
In that case, your priorities are:
1. Shelter. You don't want to waste time building one from scratch, especially if your goal is to get from point A to point B as efficiently, as possible. Sleeping bag, tent, hammock, tarp - whatever you can use to set up a proper shelter with minimum fuss.
2. spare clothing. If you need to leave in a hurry, chances are good, that you will not be properly dressed. Having an extra layer of clothing can make a HUGE difference, since clothes are your first line of defense from the elements. Shoes, even just minimalist running shoes, like vibram, or merrell (just an example) weigh next to nothing, but are a lot more comfortable to move around in, than whatever you're wearing with your suit and tie. Gloves not only protect your hands from the cold, but also allow you to handle objects that are difficult to touch without gloves. You get the point (hopefully).
3. supplies. Again - you have no time to go strangling furry critters to get food. Bring something that you can eat cold (since you may not be able to get fire/heat), and something that you can heat up (a hot meal makes a world of difference when you're cold and miserable). Bring water too. A filter straw, pot for boiling and whatnot are awesome, but 9 times out of 10 they lose to a simple bottle of mineral water you bought for $0.50.
4. Flashlight (better yet - headlamp). Since you may not have the luxury of choosing your time of departure, having a light source can be a huge help. Also pack a portable battery (10k mAh minimum, or solar-powered) to keep your phone from dying when you need it most (can also be used to charge some flashlights, etc.
5. tools. knife, multitool, portable stove, etc. all fit in this category.
