Kudzu is shown growing in the forest. Kudzu was introduced into Appalachia in the 1930s from Japan to slow erosion. Kudzu would not have been present during the period this movie covers. (Keeping in mind, of course, that in order to produce a film about the Appalachians WITHOUT the kudzu would of course require filming in another region, as to date there have been very few if any successful attempts at denuding their fast-paced growth.)
Except for Dexter Speaks, when the other characters play banjo, we hear many more notes than they actually strum.