As noted by several other board members in my PoC Spirit review thread and confirmed by Hasbro, the PoC line has several "Easter Eggs" in it. Here's what we know for sure so far, and feel free to post new Easter Eggs you know of. And by "Easter Egg" I mean stuff not shown in the instructions/packaging.
The upcoming HISS Scout can be towed by the PoC HISS.
Spirit's bow can be strung with the elastic ties that hold figures in their packages, and the removable arrow both has a working nock and the arrowhead fits in 25th style backpack holes so Spirit can "shoot" figures with his arrow.
Snow Job's gear can be arranged to make a lean-to shelter.
Cobra Commander's staff fits onto the PoC HISS.