You need to know that it is the coolest event at WDW! Most children are in costume, and lots of adults are as well. (But not everyone, so don't feel like you have to dress up if you don't want to.) They have the Boo to You Parade, as mentioned, with the headless horseman riding. They also have storytellers around the park usually, one telling the headless horseman story just before he rides in Liberty Square. They have costume contests, trick-or-treating, and free photographs with your family. The villians and rare characters are out all night as well. If you can still get a table, LTT does a special meal on these nights with the characters wearing halloween masks as well and the CMs dressed up too. There is a special fireworks show HalloWishes that is awesome and special lighting and sound effects throughout the park. You can enter MK with your ticket at 4pm even though the party doesn't officially start until 7.