On the way back you would have to be able to check in for your flight at the desks at the designated check in areas. It has to be a participating airline, AA and United are two of them. There are several more, the lists are on Disney's website and allears. It is nice, you take your luggage to the check in desk ( which in my experience has always been outside) check in and they take your luggage. I believe this is separate from the Magical Epress. You do have to check in for your flight, every person needs to be there. They check licenses, and they do weigh the bags if they look heavy. It is much easier than taking the luggage through the airport. We do it all the time and it has been great. Magical Express will still pick you up at your designated time. We usually leave our carry-on's at the resort and get them later.