The name of the movie playing at the drive-in theater was 'Cauldron of Blood'' [See: Cauldron of Blood (1968)]. The picture did not debut until 1968 which is about eleven years after the time the film is set in 1957.
Though set during the late 1950s, many film critics, movie reviewers and public audiences have commented that hairstyles in the film are from the 1970s.