Can I take the Magical Express back to the airport a couple of days after I check out of a WDW resort? We plan on going to the beach for a few days at the end of our trip.
Technically, no as this service is linked to your on-property stay. But there are loopholes for everything so I’m sure someone has one for this, too 
My first thought was: they do not confirm your airline info- they depend on the info you provide. Then I realized- you will not be a resort guest. They deliver the DME info to your room, so no- it would not work.