Revealing mistake: In the opening scene the camera pulls back from a bedside locker to an over the shoulder shot of Kathleen Turner doing her make up in the mirror. Close inspection shows that the shoulder in the foreground is actually that of a double who doesn't quite match Turner's movements.
Revealing mistake: Since they used an original game, the Monopoly's box is yellowed, whereas it should look almost new.
Suggested correction: Yes, there were Monopoly boxes of that colour, that's not yellowing at all.
Revealing mistake: Last scene in the movie is Peggy Sue waking up in the hospital. The very last shot of that scene is of the camera backing up from what appears to be a mirror. If you look closely, it isn't a mirror at all, it's actually a window made to look like a mirror complete with another set of actors to mimic the stars of the movie's actions.
Suggested correction: I don't believe this is a mistake this is supposed to show two alternate universes two different ways things are playing out.
Continuity mistake: When Peggy Sue passes out at her reunion, the first shot (from her perspective) is her on the floor, looking up at her daughter and Charlie standing about 6 feet away. The second shot is her daughter and Charlie crouching down close to Peggy Sue's face. In the third shot, Charlie is instantly standing 6 feet away again.
Factual error: Charlie's 58 Impala is a sweet ride, but his license plates don't have the requisite year stickers. His car has the '56 series of plates, and each subsequent year would require that current year's sticker.
Factual error: Her dad buys a brand new Ford Edsel. In this scene, her mom is reading the invoice window sticker. The movie takes place in the fall of 1960. The car is actually a 1958 model.
Factual error: In the scene in Bodell's Music Store, there is a copy of Al Martino's Spanish Eyes LP in the rack. It didn't come out until 1966. Also, You Can't Sit Down by the Phil Upchurch Combo was not a hit until June 1961.
Continuity mistake: When Peggy arrives at the reunion she is greeted by a couple at the front door. Lighting screens are reflected on their lenses.
Continuity mistake: When Peggy Sue goes to bed after getting drunk, her mother tucks her in. First, you see her pulling on the bed's sheet only but when the camera angle changes, she is suddenly pulling on both the sheet and the bed cover.