Factual error: Deputy Director Alvin Kersh tells Agent Doggett a story about King George III, who, on July 4th, 1776, the same day the American colonies declared their independence, allegedly made an entry in his diary: "Nothing important happened today." However, according to Arnold Hunt, curator at the British Library, King George III never kept a diary.
Factual error: After a short examination of Shannon McMahon with a stethoscope and blood pressure meter Scully definitely claims that physically Shannon is absolutely normal. However, this type of examination cannot reveal any of Shannon's supernatural abilities. In order to prove or disprove that Shannon is a supersoldier, Scully could only examine if she could breathe underwater.