CREATE TABLE table_name_12 (director VARCHAR(255), release_date VARCHAR(255), series VARCHAR(255), production_num VARCHAR(255))
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"