You have to call and order them ahead of time, and they can bring them to most sit down meals at the park, or if you are doing a character meal. If you do not want to order ahead of time, or don't plan to do a sit down meal, the Carnation Cafe, Plaza Inn bakery, and the Storyteller Cafes have them where you can just purchase them. The phone number to book the birthday buckets is (714) 781-DINE.
I had forgotten all about the Disney birthday cart, it's pretty cool too, if you just want to pick up a little birthday souvenir for your child. It's located near the Plaza Bakery. They sell little items such as birthday balloons, pins, birthday beanies, and other cute birthday themed items.
I forgot to mention these other things before: Make sure you get her a birthday sticker at City Hall, or write ahead of time and they will send you a birthday sticker (just send an e-mail asking for one, they will send it with a personalized autographed photo of Mickey Mouse. They will also mail you an important citizen sticker as well) make sure she wears the sticker all day, the birthday benefits of it are awesome! If you get a chance, ride the following rides, they offer special tributes to birthday sticker wearers:
Astro Orbitors (they will say happy birthday over the loud speaker, sometimes sing happy birthday, etc very cool ride, they usually do this automatically, but you can mention it if they do not notice)
Jungle Cruise (will lead the whole boat in a special birthday song, they do this automatically, but you might want to say hi when you board the boat to make sure they notice your child)
Disneyland Railroad (will let you ride, if you ask, up in the front)
Casey Jr Circus Train (another one you have to tell them about the birthday, they will announce it over the loud speaker)
It's A Small World (automatic, they will say happy birthday and the childs name over the loud speaker when the boats are boarding)
Storybook Land Canal Boats (automatic, but you might need to ask, they will say happy birthday to your child, let her sit up on the bow of the boat, and might lead the whole boat in a song)
Autotopia (your child will get a winning license for a free Autotopia car, very cool. They do this automatically, as long as the guy who is passing out the licenses notices your daughters sticker)
Parade Of Dreams (try and get an upfront location and the characters will come over and shake hands with your daughter and tell her happy birthday. The characters that participate very, when we went, it was the Fairy Godmother from Cinderella, the Blue Fairy from Pinnochio, one of the fairies from Sleeping Beauty, and a zebra from the Lion King)
Pin Trading - If you want to let your daughter trade pins at the park, try and get her a couple of cheap pins ahead of time to trade, keep them hidden until trading time comes. When you find a CM at a gift shop, ask them to trade with your daughter, some of them have special birthday pins they will be willing to trade, some of the birthday pins have Mickey Mouse, Winnie The Pooh, and some have the princesses. The one I traded for says happy birthday princess and it has belle (beauty and the beast) and a birthday cake on it.
Also, a cute, inexpensive souvenir for your little princess is from the leather key chain window, they have these key chains with the princesses on them, and they personalize them, and you get the key chain for $5 well it already says Princess on it, so they fill in your childs name, or your name, they have others besides princesses, these are my favorite souvenirs to bring back from Disneyland.
If you want more tips about Disney birthdays, PM me, we went on May 20 for my birthday, only I was turning 24, and the birthday benefits and perks at Disneyland, both free and low cost, made for the best day of my life ever spent at Disneyland, I would be happy to tell you about the other perks and share the photos with you from the day as well.
