Bring rice and 2 cups water to a boil in a saucepan. Reduce heat to medium-low, cover, and simmer until the rice is tender and the liquid has been absorbed, 20 to 25 minutes.
Preheat oven to 350 degrees F (175 degrees C).
Stir chili beans, tomato sauce, and 3/4 cup water through the cooked rice; bring to a simmer over medium heat. Pour rice mixture into a 9x13-inch baking dish. Spread sour cream over the rice mixture. Sprinkle crushed corn chips over the sour cream layer; top with Mexican cheese blend.
Bake in preheated oven until heated through and the cheese is melted, about 15 minutes.