Factual error: When Hopper's daughter is dying in 1978, the staff says that the pulse oximeter is dropping. Pulse oximeters were not commercialized until 1981/1983 and not in widespread use until at least the mid 1980's.
Chapter One: The Vanishing of Will Byers - S1-E1
Factual error: The boys need Will to roll a 13 to hit the Demogorgon with the fireball in the DnD game. Fireball is an automatic hit. Players roll for damage only. They mention the 13 needed to hit in the final episode as well.
Chapter Two: The Weirdo on Maple Street - S1-E2
Factual error: When Steve and Nancy are making out, the intro to "A Hazy Shade of Winter" by The Bangles plays. While the original version of the song was released by folk-pop duo Simon and Garfunkel was released in 1968, the version heard here was released in 1986, 3 years after the scene takes place. (00:52:30 - 00:55:40)
Chapter Two: The Weirdo on Maple Street - S1-E2
Factual error: When Chief Hopper and his fellow patrolman are standing over the lake, Hopper has a radio on his belt. The radio is a modern Motorola walkie talkie and at least a decade newer than it should be.
Chapter Four: The Body - S1-E4
Factual error: When Chief Hopper cuts open the fake body of Will, it appears that he opens a knife with a thumb assisted blade which wasn't invented until 1995.
Chapter Five: The Flea and the Acrobat - S1-E5
Factual error: The bus that appears in the scene is a Blue Bird TC2000 dating from 1998 to 2003, long after the setting of the series. (00:38:15)
Chapter Seven: The Bathtub - S1-E7
Factual error: When there is a pan closeup shot of the walkie-talkie the boys are going to finally talk to with the sheriff, there is a book called Great American Ghost Stories by Hans Holzer on the shelf to the left. That book was published in 1990, not in 1983, the year of the episode. (00:18:30)
Chapter Seven: The Bathtub - S1-E7
Factual error: When El comes out of the sensory deprivation pool, she's sitting on the bleachers. Hopper and Joyce are standing in front of a wrestling mat. This mat is a 2-piece Dollamur home wrestling mat. This company wasn't founded until the late 80s, didn't start using black foam nor started selling home mats of that model until the early 2000s. (00:36:10)
Chapter Seven: The Bathtub - S1-E7
Factual error: High school basket ball courts didn't have a three point line until the 1987-88 season - not in 1983.
Chapter Eight: The Upside Down - S1-E8
Factual error: When Nancy shoots the creature the second time, she fires at least 8 shots from a 6-shot revolver without reloading. And that's assuming she reloaded after firing 3 shots at the creature the first time, even though the situation made it seem unlikely. (00:20:30)
Chapter Eight: The Upside Down - S1-E8
Factual error: This error occurs multiple times during the Series but most after 11 and the demogorgon disappear from the class room a modern periodic table is shown. There's at least a 1/2 dozen elements on it that weren't discovered until the 2000's.
Factual error: During the police pursuit in Pittsburgh, the officers are wearing shoulder speaker/microphone handsets. The models are the Motorola Saber radio, which wasn't introduced until 1989, while the season takes place in 1984.
Chapter Three: The Pollywog - S2-E3
Factual error: The cordless drill used to fix door bolts in the new cabin is modern, not from the 80s.
Chapter Eight: The Mind Flayer - S2-E8
Factual error: When El arrives, Hopper rifle has a picatinny rail, inaccurate for the time period.
Chapter Eight: The Mind Flayer - S2-E8
Factual error: Joyce asks Will if he remembers when he was 8 and she bought him that giant box of crayons for his birthday - the 120 pack. Will is 13 in the show, so when he was 8, it was 1979. There were only 78 colors available in 1979 and the 120 crayons box was not available until 1998, almost 20 years later.
Chapter Nine: The Gate - S2-E9
Factual error: The military convoy has Desert Tan HMMWVs (Humvees). The Army didn't take delivery of the first ones until 1985 and they certainly were not painted Desert Tan until 1991 in the Gulf War.
Chapter One: Suzie, Do You Copy? - S3-E1
Factual error: When Dustin's toy collection "comes to life" (thanks to Eleven), one of the robots is the Transformer Ultra Magnus. Though it appears to be modified with a motorized engine that the actual toy didn't have, that's not the mistake, as there no reason Dustin couldn't have modified it. The error is that the season is set in July 1985, but Ultra Magnus wasn't released in the U.S. until 1986. (Yes, the toy was available as a Diaclone in Japan, but in a different color scheme. Dustin's has the coloring of the U.S. version, and even if he somehow ended up with the Diaclone version, it's highly unlikely he would have repainted a Japanese toy to resemble a Transformer he wouldn't know about the existence of yet, as the 'Transformers' animated movie wasn't released until August 1986).
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.
Chapter Six: E Pluribus Unum - S3-E6
Factual error: When the Russian requests the cherry flavor and refuses to talk, he gets thrown out. At the back is an oil drum from the French energy company "Total." However that logo was introduced only in the mid 2000s. (00:11:55)
Answer: This is answered in a later episode so you should watch the entire season, but if you really want to know...SPOILERS She didn't, 1 (Vecna) killed all those children.
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