I used 1/2 teaspoon red pepper flakes in the teriyaki sauce and two tablespoons chili garlic sauce in the chicken-rice-vegetable mixture. If you're sensitive to heat and spices, I would either reduce or omit one or both of those.  We didn't find this baked chicken teriyaki spicy, and rather just thought it had lots of flavor, but we also relish spicy food and aren't very sensitive to heat. Do as you see fit for your family or personal heat preferences.