The music on the soundtrack of The Pom Pom Girls was, in fact, originally a 20th Century Records self-titled 1975 album by the group Cotton, Lloyd & Christian. Copies of that album that were returned to 20th Century were repackaged and redistributed in 1976 upon release of the film. On most copies, the Pom Pom Girls title appeared on the album jacket but not on the record's label.
When Johnny and Duane are having their "food battle" in the school cafeteria, near the end, there is a drinking straw wrapper stuck to the back of Johnny's head, which disappears, and then reappears.