Evenly spread the refried beans on the bottom of a 9-by-13-inch baking dish. Spread the guacamole over the beans and then spread the sour cream over the guacamole. Sprinkle with scallions and then the shredded cheese.
To make the shape of a flag, arrange the black olives in the top left corner of the dish. Sprinkle with a dusting of cotija cheese. Spoon salsa in stripe formation on the rest of the dish. Sprinkle the remaining cotija cheese between the salsa to create white stripes. Refrigerate until ready to serve. Serve with corn chips for dipping.