Puerto Rico Film, Television, and Theatre Production Act of 2018 This bill amends the Internal Revenue Code; with respect to rules that allow the expensing of certain costs of qualified film, television, and live theatrical productions; to: (1) apply the rules to Puerto Rico, and (2) extend the rules through 2021 for Puerto Rico. (Under current law, the rules apply through 2017 for productions with costs that include a specified amount of compensation for services performed in the United States.)