Disney - Halloween
 

Does anyone know how Disney checks to see if you have a ticket for the Halloween Spookathon? If you are already in the park - do they escort you out?

I'm guessing that you're referring to the Mickey's Not So Scary Halloween Party at the Magic Kingdom. If you are already in the park they will not escort you out. However, after the offical start time of the party, if you do not have a wrist band they will not allow you on any rides, may limit your access to other venues, and will not allow you to "trick-or-treat". If you are not already in the park and have ticket for the party, they will give you a wrist band as you enter the park if you enter around/after the party start time. If you have a ticket and are already in the park, you can go back to the entrance turnstiles and obtain a wristband.

They let you know it's a separate paid event and told to exit the park at 7pm. You are then spotted by many park employees that keep you moving to the exit gate.