While on the phone looking for a new singer, Arnold says to the person on the phone, "Who?" "Bob Dylan?!"
"I've never heard of him, you get me a big name!" Being set in 1957/1958, Bob Dylan,born in 1941 as Robert Zimmerman, would be 16 or 17 and still in high school in Minnesota. He did not adapt "Bob Dylan" as his stage name until entering college.
Howard says he's going to the theatre to see Psycho (1960). The movie was released in 1960, 3 years after this episode was set.