I would think that it's very unlikely that you'll be directed to a different lot. The Mickey & Friends structure is purported to be the largest parking structure in the world. Your parking receipt is good for the whole day, so you can come and go when you want.
One thing that I note many people DON'T do - and I highly recommend doing it - is by all means take your parking receipt with you when you leave your car. Nowhere on it does it say it has to be left on the dash. In fact your receipt very conveniently lists all the various letters, numbers, and names you could possibly find in the parkage - you just grab a pen and circle the particular combination you're parked at, stick it in your pocket or wallet, and then it's easy to locate your car when you return. I can't tell you how many people I've heard/seen lamenting about not remembering where the car was parked, and wandering for a long time searching.