Fonzie (Henry Winkler) explains that his father left when he was 2. But in "A Star is Bored" (season 2), he was 12. In "Howard's 45th Fiasco" (season 3), he was 4. And in "Christmas Time" (season 6), he was 3.
The episode title is taken from the song by the American singer-songwriter Paul Simon. It was happened to be the 57th most popular single released by Columbia Records in 1972.