I liked Ors answer, but it is built on the premise that it is a single operator. The laws of physics indicate this probably not the case, and instead direct us to it being a number of sleighs, with Santa just being the boss of the company.

Most likely, the sleighs are equipped with sat phones and PLBs, and there are backup and SAR/TRAP sleighs staged around the globe, so pick up the payload and carry on with the mission while the busted sleigh's crew is evacated and the ride either lifted out or destroyed in place.

As far as the kits go, odds are they are built using the technology as the toy bag, and are fully equipped for most outcomes. In case of a water landing or extremely adverse conditions, pull the pins on the PLB and the strobe on the outside, crawl in, tie it off, and open an air bottle. You should float, or be isolated from the elements. Wait for pick up.

That of course assumes that the elves aren't merely serfs. In which case, they may be disposable.