Normally, the wishes that made Karyn (now Delores) transport to New York and Jon (now Rudolph) transport to Canada wouldn't work, because both of those places were outside the stone's range. But these weren't normal circumstances.
Pete didn't know it yet, but his family had a background in magic. It was this familial attribute that allowed him to amplify the effects of the wishing stone.
This was obviously bad. The stone was already dangerous enough as it was, but if Pete could amplify its effects ... it could be even more dangerous, especially since Pete was on a power trip.
Since the moment he turned Jon into Rudolph the Retard and Karyn into Delores the Stripper, a week ago, Pete had made several changes around town.
The first thing he did was make a few wishes about Sarah McMillan ...