Hi Rebecca!
I'm so sorry to hear about your Mr. Potato Head mug. Unfortunately I can relate. I've had multiple instances of ornaments breaking, no matter how much I wrap them, in my luggage on the trip home.
The Disney Store has a "Disney Parks" section of their website where you can buy some of the merchandise sold in the parks. Upon doing a quick search of the Mr. Potato Head mug, I didn't see a match.
Another option is on the
My Disney Experience app, there is an option to buy authentic Disney Park merchandise. You can certainly check on the app to see if the mug you bought is available.
If that doesn't work, what I've done in the past is ask a friend who is visiting to pick up an item for me and mail it to me, and of course I reimburse them for the merchandise and shipping.
The past couple of trips I've actually scanned merchandise in the Disney Store in the park and then bought it in the app and had it shipped to my home so I didn't have to tote it. I know that doesn't help you for this instance, but on a future trip this may be a good option.
Magically,
Stacy