Even though glass containers are prohibited in the theme parks, there is an exception for small glass containers for feeding your baby. I called Guest Services and spoke to a Cast Member who confirmed with me that small glass baby food jars and glass baby bottles are allowed into the theme parks.

Yes, you are absolutely allowed to bring baby food into Disney World. Disney has a very generous policy regarding outside food, especially for infants and toddlers. While glass containers are generally prohibited in the parks for safety reasons, Disney makes a specific exception for small glass jars of baby food. You are also permitted to bring breast milk, formula, and juice in bottles. For your convenience, every Disney theme park features a Baby Care Center, which provides a quiet, air-conditioned space for feeding and changing. These centers are equipped with high chairs, microwaves to warm up food, and sinks for cleaning bottles. When entering the park, simply inform the security cast member that you have baby food in your bag; they will perform a quick check, and you’ll be on your way. You can also bring a small cooler (no larger than 24" x 15" x 18") to keep items chilled, provided you use reusable ice packs rather than loose ice.