It is a halloween party at MK, it runs so many nights a week during the month of Oct. and the park closes on these nites early, they empty out (people who have tickets for this event get to stay in Fantasyland, i think til they re-open) Yes you buy special pass for one specific night. The kids and some adults get dressed up in costumes for halloween. There are special characters all over and a special halloween parade (the characters are all dressed in different costumes) And certain areas all over the park to collect treats! They give out treat bags for it.
Near Buzz lightyear ride, inside they do free family pictures. We had gone the first year we took our kids to Disney DD (7) and DD (8) and they were dressed as Buzz and Cinderella...............Got the cutest picture of my son with Buzz, and many precious pictures of my Daughter with Cinderella herself right by her pumpkin coach that was all lit up! It is something I think everyone should do once in their lifetime!!! Some may say the price of the tickets isnt worth it, I don`t agree. Make sure you check out which days they are incase you decide not to do it, have hopper passes and end up at epcot or MGM those nights. Plan ahead ...............have a great trip no matter what you decide!!