As to the "leaking", I tested several apples, both Tamiya and Impact. I used masking tape, electrical tape and aluminum foil tape. I started by taping one of the prisms of the pyramid shaped mirror, and worked from there. With the entire top of the apple taped (tape was flush with the top of the LEDs), we were still getting hits. Thus, our resulting opinion that the LEDs were the only place an IR signal could be entering the apple body from.
We also found that the Impact apples were slightly more sensitive than the Tamiya ones.