It's been 3 years since we've been to WDW and last time was the same time of year. I vaguely remember at that time that some kids/adults do wear costumes into any of the parks on Oct 31 (obviously no trick or treating or anything). Is that still the case? I have a 16 year old daughter who is considering wearing a Belle costume dress (not full length) and she is wondering if that will be allowed. My other daughter is 13 so according to policy she is still allowed to wear a costume anytime (last trip for her to be allowed for that).
Maybe nobody knows?
It would be safe to assume that the regular non-party costume rules apply, since it's not a party.
To my understanding, officially you can't be dressed up until party time however party goers can enter at 4pm. Last year my entire family dressed up from 4-7 before we left, because we didn't have party tickets. Kids under 12 can dress up any day, any time. I would think on Halloween they would be more lenient, however, I'd have other clothes as a back up. Hope that helps. Anyone feel free to correct me if I'm wrong in anything I've said. I've been off the boards for a few months. I'm a little rusty.