In the early scenes of the town's women gossiping, several are on telephones. The phones have dials, but Mayberry does not have dial telephone service. When Andy and Barney make a call from the Sheriff's Office, they must ask Sarah, the operator, to make the connection. A small town like Mayberry would only have one telephone exchange and the types of phones provided by the telephone company wouldn't mix dial and non-dial phones in the same exchange.
As usual, calendars are multiple and don't match, seeming to represent July, 1960 and December, 1960 rather than the January, 1961 time setting.
The long shot of Aunt Bee and Emma, across the street, shows obvious stand-ins.
The "TV Guide" displayed on the top shelf of the magazine rack to Andy's left as he enters Walker's Drug Store to talk with the gossiping ladies features Lucille Ball on the cover, but it was published in the '50s and the episode is set in the early '60s, as evidenced by the 1961 Ford Galaxy police car.
In the final scene, when Aunt Bee walks into Andy's office, she pushes the door behind her to close it, but it doesn't close all the way and a hand can be seen pulling the door shut. Update by some else: Just watched this episode and the last 1/3 of the show takes place in and outside the hotel. Aunt Bea never goes into the sheriff's office except once in the beginning and the door isn't in view when she shuts it.
A boom mic is reflected in the windshield of the squad car.