Harriet refers to Sterling as her second cousin, on her mothers side, once removed. Although later in the episode, Nellie refers to Sterling as her uncle.
At the beginning of the story, Mr Garvey is hanging The Pen and Plow sign for Mrs Olsen. She tells him it's perfect, but in fact it is a little crooked. Later in the story, the sign is hanging perfectly straight.
"Repetitious" is spelled incorrectly at the spelling bee, yet nobody seems to notice.
When Harriet is going to have her sale, she says she plans to raise the list price of the items by thirty percent, then sell them for twenty percent off. She then says that she can make a ten percent profit on everything she sells. This is wrong mathematically. The actual profit on a sale like this is only four percent. For example: If an item costs one dollar, raising the price by thirty percent will make it one dollar and thirty cents. Lowering the price of that by twenty percent amounts to a twenty-six cent discount, making the total price one dollar and four cents - only a four percent profit on the original cost of the item.
Laura told Mrs Oleson that Murdock went to the telegraph office for more newsprint. Newsprint is special paper in 24x36 inch sheets designed for printing press. No telegraph office would have them.
At 17:27, Harriet Oleson Accidently calls Alice Garvey Allison Garvey.
Charles refers to the Pen & Plow as "yellow journalism," but the term wasn't coined until 1895 during the newspaper circulation wars in New York City.
Xanthophyll is the last spelling word. The chemicals were discovered in 1907, decades after the events in this episode.
The newspaper office is supposedly in the vacant bank building, but the bank never had a brick front when Charles and Edwards built it.