One popular Disney World-related question this time of year is regarding what you can and can’t wear as a costume into the Magic Kingdom for Mickey’s Not-So-Scary Halloween party after-hours event. Thankfully, Disney has released this helpful video that should answer most of your questions.
One thing worth noting: Central Florida can still be very humid and hot this time of year. If you are attending the Halloween parties in late September/early October, it is wise to have a backup outfit just in case it is too hot for costumes. I went to the party in late September last year and it was well over 100 degrees and very humid even in the evening. We opted to go in more lightweight park attire and found that about 90% of the visitors that night skipped the costume as well. As with anything involved in a Disney World trip, just be sure to plan ahead and check the weather!