At 5:40 Grandpa is seen pouring some of his coffee from his cup into his saucer, and drinking it from the saucer. This was an old-time way of cooling the hot coffee quicker; saucers allowed the coffee to cool faster by spreading it over more surface area.
In the spring of 1972, while filming this episode on location in Frazier Park, California, a camera crew was tasked to spend a couple of days filming various beauty shots of the mountain scenery. These can be seen throughout the run of the series, usually used during Earl Hamner Jr.'s opening narration.
The speech heard on the Radio is Franklin Roosevelt's second Inaugural address, made on January 20, 1937. (This is almost four years out of sync with the time line of the series, established by incidental information on recent episodes as the spring of 1933).
Olivia is selling a quilt. She points out that a piece of the quilt is from MaryEllen's infant baptism gown. The Waltons are Baptists. Baptists do not baptize infants.