Table schema:
CREATE TABLE table_name_12 (director VARCHAR, release_date VARCHAR, series VARCHAR, production_num VARCHAR)

Question: Who was the director of the movie having a release date of 1934-09-15, an MM Series and a production number less than 6494?
SQL: SELECT director FROM table_name_12 WHERE series = "mm" AND production_num < 6494 AND release_date = "1934-09-15"