Factual error: When Mary Ellen brings G.W. into the woods to practice dancing together, she opens up a magazine and shows him a movie still of Fred Astaire and Ginger Rogers. The problem is the photo is a still from Fred and Ginger's dance in the movie "Swing Time" (at 00:28:00 within that movie) which premiered August 1936 (and was filmed that year), but this episode takes place more than two years prior, in early 1934. (00:59:20)
Factual error: After Olivia realises she has polio, when John goes downstairs the radio is on and we hear an excerpt from President Roosevelt's fireside chat about upcoming Labor Day. The problem is this aired on the radio right before Labor Day in 1936, but Olivia contracts polio very early 1934. (00:22:35)
Factual error: When Olivia gets polio, she is at home. John is allowed to stay with her 24/7. It seems unlikely that the doctor, even if not taken to hospital, would allow John to stay in the room and risk contamination.
Factual error: When John-Boy and Jason walk into the theater, there's a poster for the movie Breakthrough, released in 1950, which is about the Battle of Normandy that didn't even happen until Summer 1942. This episode was set in early 1934. (00:50:55)
