Contreras started as key grip on the television series The Waltons (1974-1976) and worked then as key grip/ dolly grip on films such as action drama Convoy (1978), the adventure Tarzan, the Ape Man (1981), the music drama Staying Alive (1983), the comedy Micki + Maude (1984), the television special Police Story: The Freeway Killings (1987), the comedy Wayne's World (1992) and its sequel Wayne's World 2 (1993), the comedy Mr. Saturday Night (1992, with Julie Warner and Mary Mara), and the thriller Primal Fear (1996, with Alfre Woodard).