Near the end of the film, Norman is watching TV and the tune emanating from the show he is watching is the theme from Monsieur Ed, le cheval qui parle (1961). Alan Young, who plays Norman, was the leading man in that old TV show.
The three main middle-age stars were all part of iconic shows or movies that began in the mid 1970s: Mark Hamill in Star Wars: Épisode IV - Un nouvel espoir (1977) and several of its sequels; Erik Estrada in Chips (1977), and Cindy Williams in Laverne et Shirley (1976).
Cindy Williams had previously appeared in the film Morten Belvad, which also takes place in 1962 as does part of this film.
The name of the character played by Erik Estrada is 'Earl', but everyone calls him 'Duke'. He reveals the reason for the nickname when he refers to himself as 'Duke the Earl', an allusion to Gene Chandler's 1961 song "Duke of Earl" that charted number 1 on pop and R&B charts in 1962.
In a classroom scene, the teacher asks the students to identify the Secretary of State under Grover Cleveland, but the answer to that question is never given. There is really no reason why a high school student should know that obscure fact From the 1880s (or even care), but in case you're curious about the answer, the name of Cleveland's Secretary of State was Thomas F. Bayard,