I have been in the military (Army) for 19 years now. I have been "Active Duty" and "Reserves".
All that you need to qualify for the Military Discount is a valid ID card, otherwise known as a CAC Card, or "Common Access Card". Anyone that is currently "Active", meaning currently serving in the Active Components or Regular Army, Reserve Components or Enlisted Reserves, and the National Guard qualify for the Military Discounts. All that you need to show them is an ID card that is not expired.
A lot of Cast Members, and normal everyday people, confuse the term "Active" as meaning Active Components. There are other options for someone to transfer out of the military into an IRR group, or "Inactive Ready Reserves". These members are still on the military's "books", under their current contract no matter how many years remain on their enlistment, and can be called up if needed. They do not actively serve (whether it is one weekend a month and several weeks a year or every day). They simply do not show up to any trainings or events unless mobilized for a deployment, for the most part.
This is why ALL military ID cards no longer distinguish between the Regular troops, the Reserve troops, and the National Guard. As long as they are "actively serving" their military obligation contracts, they are an active member of the military.
I hope this clears it up. This might explain why the Cast Member was referencing the deployment orders, or mobilization orders, because a member of the IRR will get issued those orders to deploy, thus bringing them from Inactive to Active.
So for the sake of explaining to a Cast Member or non military member all of these differences, my recommendation is to say yes when asked if active, give the unit's general location, and smile and say thank you for the extra discount.
My background is 18 months in Iraq, 14 months in the Horn of Africa, 6 months at Arabic linguist school, 6 months training deploying troops upon my return from Iraq, being US Army and attached to British (UK) units and US Marines alike....just a melting pot of unique missions.
I hope that I have helped clear up things for you.
Have a Magical time!!!!!