Hiya Heather! First off, I wanted to extend my congratulations to your family, how exciting! This will be a gender reveal that will be magical in every way, and while smoke poppers are not allowed at Walt Disney World Resort, I have a few magical alternatives!
First, you can pick up a green Celebration button at City Hall (right next to the entrance of Disney's Magic Kingdom Park on the left side). From there, head on over to
Ye Olde Christmas Shoppe, which is to the left of Cinderella Castle in Liberty Square, to get your button personalized with the baby's gender on it. Alternatively, you can also head over to Disney Springs ahead of your visit, stop at
Disney's Wonderful World of Memories, and purchase baby's first set of Mickey ears (you can get them embroidered here!), or pick up a cute onesie from
World of Disney that matches the baby's gender to display in the photo. My final magical alternative is purchasing balloons from the balloon vendor on Main Street, U.S.A. that your daughter and son-in-law can hold for the picture that matches the baby's gender.
I hope these alternatives work out for your family, Heather. Sending you and your family the warmest congratulations, and have the most magical visit to Walt Disney World!
Frances