Ah! It's true about snow globes! I bought one at Christmas when I visited my mom and packed it in my carry-on. Bad idea. Luckily, my mom was there to take it back home again. I brought packaging with me this previous visit and put it in my checked luggage.
If you decide to buy one, Disney is very good about packing stuff, but if you have a ziploc bag, maybe also put it in that, too.