Hey There, Hi There, Ho There, Elizabeth!
You are as welcome as can be here at planDisney. It looks like your vacation is just around the riverbend, and soon, you'll be transported into a whole new world of magic and making memories.
Elizabeth, I double-checked with Guest Services, and while you purchased an
adult ticket for your 3 year old, it won't impact him being able to enter the theme parks. But you did pay more for an adult ticket than what a child ticket would cost. The good news is that he has a ticket, and he will be able to enter.
If you would like to see if it's possible to change his ticket to a child ticket, you can call
Disney Guest Services before your trip or visit the Guest Services window prior to entering the park. While typically, tickets are non-refundable, they may be able to change it to a child ticket, and you could see if they might be able to refund the difference. They don't typically do this; however, it never hurts to ask.
But, if you leave the tickets as they are, he should not have any problem entering the park and living his best Disney life. My kids have grown up visiting Disney, and each age and stage has allowed us to enjoy the experience in a new way. I hope you both enjoy the most magical vacation on earth.
If you have any further Disney vacation planning questions, stop back here to see me. I'll be right here, at the second star to the right and straight on 'til morning.
See ya real soon!
Keri