In a previous submission, it is suggested that at the end when Mr. Ingalls says he will have enough time to turn the wagon around, but when Mrs. Ingalls leaves the store, the wagon is facing the same way. If you look closely, when they arrive they are on one side of the store and when Mrs. Ingalls leaves the store, they are on the other side of the door, meaning the wagon was turned and is now facing the opposite direction.
Towards the end of the episode, Mr. and Mrs. Ingalls and their daughter Carrie drive up to the Oleson's Mercantile so Mrs. Ingalls can drop off some eggs. As she climbs out of the wagon, Charles says he will turn the wagon around and drives off. However, when Mrs. Ingalls comes out of the store, the wagon is still facing the same direction it was when they drove in.
The Home Mechanic book that Charles is reading in bed wasn't published until 1903. The time line is late 1800's.
When Nels opens the door of the store after the fight if you watch closely one of the women coming in the door is actually a man dressed as a woman. The couple before the Ingalls enter the store.
When Charles tells Caroline that the Olesons have been building to a fallout for years. How does he know that? They've only been in Walnut Grove for a short while. Not years.