The room service menu is free 24/7. You can order coffee/milk, iced tea, lemonade with room service and it is free. Smoothies, sodas, and alcoholic beverages are charged.
I'm not aware that they will bring you "bagged snacks" or stuff like that, although you can purchase that stuff right outside the theatre, bring your own, or get M&Ms from the ice cream station!
Any of the beverages listed on the breakfast menu are free 24/7 from room service.