Factual error: As Homer and his friends attempt to flag down the train after dislodging the old rail, the engine seen is of the 2-8-2 wheel arrangement with markings of the Norfolk and Western Railway. The Norfolk and Western never owned any 2-8-2 locomotives, preferring instead engines of the 4-8-0 arrangement.
Factual error: This movie takes place in 1957, clear from the Sputnik reference, but at the dance they play "It's All in the Game" which didn't come out until 1959.