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.
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.