Howard Cunningham states William Shakespeare gave the quote, "To Err is Human, Forgive Divine." Alexander Pope is credited with the quote.
When Ralph comes to Arnold's to tell Richie he's running away they go into the men's room to talk. They enter the door to the left, with a door 2 feet to the right for the lady's room. Inside the bathroom there are sinks where the door to the lady's room should be indicating that the doors are mislabeled or they used the wrong set.
When Marion Cunningham is making breakfast, a polystyrene foam carton for eggs is seen on the counter top. Egg cartons in the early 1960s were made of pressed and formed paper pulp. Foam cartons did not come onto the market until 1967.