Reference on the radio news broadcast to the Dillinger Gang's bank robbery in Greencastle, Indiana, places the action of this episode around the date of that event: October 23, 1933.
When Grandpa (Will Geer) is sitting in the living room and says, "And the great star early droop'd in the western sky in the night," he's reciting from Walt Whitman's elegy for President Lincoln, "When Lilacs Last in the Dooryard Bloom'd." Geer had portrayed Walt Whitman on stage, and so knew these lines well.
One of two episodes from the first season where a ne'er-do-well cousin of the Baldwin sisters attempts to steal the recipe. The other one is The Reunion (1972).
Most of the forests, mountains, creeks and rivers referenced on the show are real, however this is one of the few episodes that mentions a completely fictional geographical area. In this case it's Grandpa's desired burial site, the Cyclamen River, which doesn't exist.