I've noticed this on a couple of occasions. Some hard hit shots, usually coming off the top right flipper will go right through these Neutral Zone hole (and the one below it, can't actually remember what its called) and the ball will end up in the loop/orbit.
Also, sometimes the Neutral Zone hole will occasionally trigger the below hole, not sure if that's related.
Also, sometimes the Neutral Zone hole will occasionally trigger the below hole, not sure if that's related.