Factual error: Laura Ingalls Wilder was born in 1867. Ralph Waldo Emerson died in 1882, which means she was at the maximum 15-16 years old (and already married) in order to meet him IF he were to appear in 1882 which is not possible because: The problems with his memory had become embarrassing to Emerson, and he ceased his public appearances by 1879 (according to wikipedia).
Factual error: When the hot air balloon comes down with Carrie in it you can see N410AA printed on it. This is commonly called a tail number on planes and is issued through the FAA, which of course did not exist during the time period of the episode.
Factual error: Albert has a band-aid on his left hand. Band-aids weren't invented until 1920.
Factual error: As the train is going backwards from the oncoming caboose, the camera pans to the field background and if you watch from right to left, you'll see a white vehicle driving in the background. (00:42:20)
Factual error: In the remastered DVD editions, on Doc Baker's wagon, you can see that the canvas wagon cover has a plastic window sewn into it.
Factual error: This episode was mentioned by Laura at the beginning as taking place in December 1889. Rose was born in December 1886, so she should be 3 years old now, but she is shown through the episode appearing only to be roughly 6 to 12 months old and still in a crib.
Times Are Changing (2) - S9-E2
Factual error: This episode takes place around 1886/1887 and in the episode Royal dies. In real life, Royal didn't die until 1925.
The Nephews - S7-E14
Factual error: Royal Wilder promises to give his sons an Indian Head nickel if they are well behaved at Almanzo's/Laura's house. The Indian Head nickel was not minted until 1913 - 30 to 40 years later.
Factual error: Right as Michael Landon boards the train off his horse you can see a radio tower in the background. Radio hadn't been invented when the show was set.
Factual error: A modern day fire extinguisher is shown on a beam Charles walks next to in the town of Bixby.
Factual error: When the older boys are lying around the playground discussing The Election, you can see the bottom of the boy's shoe. It is made of molded rubber and features a "tread" on the bottom. This would not be how shoes were made in that time period.
The Campout - S2-E5
Factual error: This episode takes place almost entirely in the mountains. In Minnesota where the show is set, there are no mountains as tall as shown, particularly those that are snow-capped and rocky. The show was shot in California.
Factual error: Adam Kendall goes to Minneapolis to take the entrance exam to law school. He meets a fellow student who, after the first exam, accompanies him to the "EL (the elevated train) " Minneapolis never had an elevated train, only Chicago.
The Raccoon - S1-E10
Factual error: Laura and Caroline are playing a word association game about beverages and Laura says "orange juice, " which wasn't used by Americans until the 1920s. Any earlier than that, oranges were a luxury not available to farmers in Minnesota.
Factual error: When the man is holding onto the rope from the balloon, you can see modern tire tracks in the field.
Factual error: Aeroplane trails are in the sky throughout several episodes. This wouldn't have been possible in the time the show is set.
Factual error: On the hill to the right of the kids as they walk away, there appears to be a telephone tower on the hill.
Suggested correction: Wasn't Mary the one in the balloon?
Mary was in the balloon earlier in the episode with the man who runs it but near the end, Carrie wondered off into it and it took off with her inside ALONE.