Knott's and Universal both do scary Halloween things, so why not Disneyland?
Here's an idea.
They turn It's a Small World into It's a Scary World during Halloween.
But from the outside of the ride, you won't see any change. No, the outside facade of the ride will remain the happy IASW everyone knows and loves. However, as soon as your boat goes inside you're greeted by the happy and smiling dolls singing the same song over and over again; only they're in various stages of PG-13 slasher movie death.