Asked the staff about gluten free flavors and none of the three working at the time could not answer if syrups were GF. (Got "I don't know"s instead of "let me check"). So I went off of previous review. I had no issue with the flavoring (I react to fairly small amounts). All I had was a cherry snoball, and while the flavor was ok, I didn't have a reaction.
We called in advance of going and spoke to staff who informed us that the ice cream and sno-cone flavors were all gf. Toppings are not but we were able to get my celiac a cherry snowball that she loved.