Random thoughts:
I'd consider using a couple of the following on the outside of the case instead of the GID tape:
http://www.thefirestore.com/store/product.cfm?pID=305It is both retro-reflective *and* GID. Doing that, you probably don't need the material *in* the kit as they could use the kit box itself as a reflector/marker.
Here are some photos of Gloflex (reflextive + GID vs a high quality GID tape):
http://navitsky.org/photos/gloflex/(kit with reflective decals, attached to the cord could be swung as signal device, for example)
Like others, I'd probably drop the toothbrush, pick and GID sticks. I think the coin light stands in for the GID sticks anyways -- just protect against accidental activation.
I'd also probably drop the Lifesaver as it is just going to get nasty over time. If you really want a glucose tablet, I'd just include one. They don't get as nasty, come in individually packed, and have expiration dates.
Personally, I'd try to get a bigish (4"x4", or at least 4"x3") non-stick pad in there. You can use it with the duct tape and handle larger wounds.
You might consider swaping the pencil for a mini Sharpie. The Sharpie can be used to write on doors, whatever to leave messages where the pencil won't be able to.
I know you decided not to have meds in the kit, but I think some Aspirin would be a good idea. And anti-diarrheal as well.
You might be able to use the cord to attach the whistle in such a way you both don't need some inside the kit, and potentially could include more.
The safety pin idea is good.
A mirror would be nice, but not sure if you have the space budget even if you remove items.
I'd like a packet of burn gel, can be used with the 4x4 pad as noted above.
Personally, I'd also like a 4x4 BloodStop gauze, but it is pretty expensive and I suspect some here won't agree.
http://www.yylabsmedical.com/product_inner_details.php?id=20Fold flat N95 mask would be good.
A pair of Nitrile gloves can come in handy.
As a sidebar, many retro-reflective tapes are fully sealed. Agreed, the stuff that looks like gray paint is not.
-john