Factual error: In the opening seconds of the intro the BTK killer is following a woman home in his work van. Both the woman and BTK have license plates on the front of their vehicles. Kansas does not use front license plates. (Also, BTK's van shows the county abbreviation on the plate as WY - Wyandotte County - where Kansas City, KS is located nearly 200 miles away. The county tag abbreviation should be SG for Sedgwick County).
Factual error: The episode is set in 1977 and Edmund tells Ford that Frances Farmer had a lobotomy. However, the first report of Farmer having a lobotomy came from the 1978 novel "Shadowland" by William Arnold. It was subsequently revealed that some of the events were completely made up by Arnold, including the fact she had a lobotomy. There was never any allegation or suggestion that Farmer had a lobotomy while hospitalized in the 40's.