Jon ran through the fading mist and found himself back in his neighborhood. Breathing a sigh of relief, he then ran back home. He momentarily thought about heading to Karyn's house, but it was in the middle of the night and he wasn't sure his best friend would be too happy to see him.
So he headed home. And when he got back, he fell asleep in exhaustion. He really wasn't much of a night person.
The next morning, Jon woke up and recalled everything that had happened the previous night - stopping those workmen from taking Biff, finding the warehouse in the mist, then ending up losing Biff to the workmen anyway. It definitely wasn't a dream. He also remembered Karyn's impending doom and decided to head over to her house. Before he left, though, he decided to take the stone with him.