25. The PC's wake up in town, only to find that humans can't speak and behave like they have the intelligence and passivity of sheep. Meanwhile, all domestic animals (horses, cats, chickens...) speak common and have average human intelligence. They have no past memories from before they woke up that morning.
27. Last night, a fog passed through the town, and everybody who was caught outdoors during it was turned to stone.
28. In a local cathedral, the PCs view a fresco of a party of adventurers who lived long ago, and are surprised to find that the resemblence between themselves and the long-dead heroes is so precise its almost like looking in a mirror.
29. The pond that was in the middle of town is now a hundred feet further north from where it was. If you watch it, it seems to slowly moving northward, getting faster and faster...
30. All of the dogs in town turn into equally large frogs, and the frogs turn into equally small dogs.