A couple of thoughts...a medium/small compass and a map of Philly. There are a couple of companies that make walking around (meaning non-topographic/street) maps of DC, Philly and so on. Some can fold up to about 3x5 and when folded out show remarkable detail. I picked up mine at the train station in Philly. Of course if that doesn't fit the bill mytopo or a gas station are fine alternatives. It's surprisingly easy to get turned around. (Streetwise is one company and PopOut Maps from Compass Maps is another, just for examples.)

Since we're talking a small knapsack I would opt for a small, but not PSK-sized compass. (adding a PSK like the Ritter PSK wouldn't be a bad idea). You might also consider a survival straw, but then again I might also add a Sierra-type cup, a spork, a few pre-moistened towelettes (like you used to get a KFC) and a 400 kcal ration bar.

Personally I would ditch the mylar blanket and go after an AMK heat-sheet or AMK bivvy and a four-pack of those air-activated pocket heater packs. The heat-sheet is a bit bigger than a space blanket, but the space blanket is really nothing much, but the same material those mylar helium balloons are made of. A suggestion down at Wally World for about 79 cents, buy a space blanket, open 'er up, put on your usual jacket and go step outside for about half an hour. Tomorrow might be even better since we're supposed to get some rain in the region. Just a thought...

Emergency poncho might not be a bad idea.

I would also recommend adding a small waterproof or drybag large enough to put your essentials in and seal, like your phones and wallet. The couple of times I've had trouble with my commute the weather was always a factor and usually it was rain, lots of rain.

I think you have too many quarters, but that's just my opinion. I carry about $3 - 5.00 worth and a cheap pre-paid phone card. The coins will let me pay a third party for the use of their phone and I can use the phone card if a pay phone is working. More than that is more weight than I want to cart around.

You might add a bandanna or two as well (maybe one bright orange and the other blue or green if they don't have a gang affiliation).

Possibly 60 or so dollars in cash in a sealed packet (2x 20, 1x 10, 1x 5, and 5x 1 as a possible mix). If that is enough to pay for a taxi or third party to get you elsewhere.

Finally, a laminated 3x5 with your emergency contact information, critical medical info (allergies, etc.)

Just my thoughts and there are probably good reasons why these are bad ideas.