Hi Shannon,
Thank you for your kind words! We really love spreading pixie dust to our guests!
There are always various discounts available to military and non-military personnel for the Walt Disney World Resorts. These change frequently and there are no guarantees that what was offered one year will be offered the next.
I am not sure if you can get a discount on the Mickey's Not So Scary Halloween Party specifically for the military. However, there is a great website which can help you. It is called ShadesofGreeen.org and they can provide you with the discounts for the military while in the Orlando region.
In addition, I would look on Mousesavers.com for any discounts as they list discounts as well that are legitimate. I often hear stories of guests who purchase "discounted" tickets and they are not valid when they get to the park.
Finally, if you already have your tickets, I am not sure they can refund you the difference but it never hurts to ask.
Thank you and your family for all you do to keep us safe and have a magical vacation!
Beth