Ate the french fries, didn't have any issue. They have gluten free bread and claim the burgers are gf. Was too scared to try though. But they're a good stop if its late and you're desperate.
They offer gluten free bun wich is very good. You can choose the classic burgers like Quarter Pounder or Bigmac. The fries and sweetfries are also gluten free. And according to the webpage the sundae is also gf.
— Gluten-free items are marked on the main menu