Factual error: The word "floaties "was not used to refer to pool toys in the 1950's.
Factual error: When in Harrisburg, Susie mentions the Civil War Museum, but that didn't open until 2001.
Factual error: Abe hilariously exercises in a ridiculous suit while listening to Robert Preston's "Chicken Fat" recording. But Preston (who starred in The Music Man) didn't release this until 1962, at the behest of President Kennedy, who was big on physical fitness.
Suggested correction: It's true that this song was not recorded and released until 1962, which is a little after when this scene takes place. However, Abe is not actually "listening" to it (or any other music) while he is exercising on the lake dock. The song is used as part of the series soundtrack and creates a desired mood for the scene. As the storyline is now in the early 1960s, it is appropriate to the era, and is only background music.
Midnight at the Concord - S2-E5
Continuity mistake: When Benjamin is driving Midge back from the Catskills to New York City, he briefly is driving on the left-hand side of the two-lane country road (which is not a one-way).