Chapter Five: The Flayed - S3-E5
Factual error: When Eleven is handed M&Ms in the hospital she is given green and red. Red M&Ms were not reintroduced until 1987. (00:42:28)
Chapter Five: The Flayed - S3-E5
Factual error: When Hopper steals the yellow convertible at the gas station mini mart, the gas pumps have vapor recovery boots on the nozzles. Those weren't in use for another half decade.
Answer: The body was fake, made by the scientists at Hawkins Lab in an attempt to cover up his disappearance and the existence of the Upside Down.