This is the first time that Helen Crump is referred to as Andy's fiancé.
When Floyd is telling Goober how much money a famous author can make he actually has it backwards. Writers who are just beginning are paid by the word, while established writers get paid in commissions, royalties, and percentages. On the other hand, an average-length novel, at $.20 a word, could bring upwards of $18,000; a significant amount at that time.
When Aunt Bee pulls Opie's toast out of the chrome toaster the top has been artificially dulled to prevent the audience from seeing reflections of the studio lights, cameras, and other structures. This is a common practice in television, most often seen with the high-gloss finishes on darker automobiles. A close-up shot of the top of Aunt Bee's black car door in "Opie Steps up in Class" shows this treatment.
This is the only color episode where Andy is shown taking his date (in this episode it was Mavis Neff) to Myers Lake at night.
When Andy drives up to Helen's house, the squad car has a black license plate with amber lettering. This was the official color scheme of California license plates in the 60s.