Chapter Six: E Pluribus Unum - S3-E6
Corrected entry: Lucky Charms didn't add rainbows until 1992. (00:37:00)
Correction: To clarify the other correction, there is a rainbow on the box, but not the rainbow marshmallow. In fact, the box seen is from a 1985 limited edition Lucky Charms box where the marshmallow colors were mixed up. In real life, that box did have a rainbow on it. Season 3 is set in 1985.
Chapter Five: The Flayed - S3-E5
Corrected entry: When Steve Harrington knocks out of the soldier, Dustin congratulations him. Over Dustin's left shoulder there's a black silhouette of a crew member hiding in plain sight. (00:36:50)
Correction: Actually that's Robin's reflection. You see the mouth closing at the same time.
Correction: The lucky charms box didn't have rainbows, like the marshmallow, it was the background of the box that made her have a flashback.