About the 8 year old:
- road map: can he read it, know where he is, or use it to go where he needs to go?
compass: can he take a bearing, and navigate (with the road map)?
mess kit: nice, but you've given him 2 MREs, mess kit not necessary for that.
MREs: I'm sure he has seen uncle wildman heat up an MRE, knows how do to it himself?
Tarp: does he know how to create a shelter for/by himself?
2 knives: 8 year old, I know in LA they're all outdoorsmen, but are you sure he knows how to use a knife safely?
Hand warmers: every 8 year old loves these; for pure hand warming, also give him a pair of cheap fleece gloves.

Maybe add:
Clothing: kids can get by with what they have on, and LA is pretty warm most times. A hat to protect from the sun. Consider a sweater, change of underwear, and socks in the kit. Keeping BOB clothing current is really hard for young kids, they grow out of them every 3-6 months.
Trash Compactor bag: line the backpack and keep most of the clothing and bedding dry in the event of rain.
Rain parka: here I'm ignorant of LA weather and what folks do, but here in the PNW we put a premium on staying dry all the time.

Total weight on BOB: where do you expect the 8 yr old to bug out to, how far does he carry this kit?

Good kit, great gift: it looks like he is either a budding outdoorsman, or would benefit from some hands on instruction to go along with the BOB.