It is pretty standard practice for both of us to get a seat to know where we are sitting, then I exit to get dinner at Farmer's Market area and bring it back for us to eat while we wait for the show to begin. I've done this a couple of times with no problem.
We also will take turns going to the restrooms just outside the arena. We just make sure we are back before the show starts. I have noticed that the Cast Members kept telling us that if we leave we were not guaranteed reentry, but its the bathroom for goodness sakes! When we tell them where we are going, we usually get an "Oh, OK." from them.