Revealing mistake: Penny is held captive in her bedroom, the window covered by bars. Seaweed shows up to 'rescue' her, brandishing large wire cutters and clips the bar on her left, but you can see the bar on her right is pre-cut as he bends both, just before she climbs out the window.
Hairspray (1988)
1 revealing mistake - chronological order
Directed by: John Waters
Starring: Divine, Debbie Harry, Deborah Harry, Ruth Brown, Sonny Bono
Factual error: Although the film is set in 1962, it uses the song "You Don't Own Me" which wasn't released until 1963 (and didn't become a big hit until 1964).
Tracy Turnblad: Mother, we're watching "The Corny Collins Show."
Edna Turnblad: Penny, your mother called all frantic. She said you are punished.
Penny Pingleton: I'm always punished.