Other mistake: While Dennis is editing one of the video tapes, there's one on a table labeled "89" even though the film takes place in 1988.
Paranormal Activity 3 (2011)
1 other mistake - chronological order
Directed by: Ariel Schulman, Henry Joost
Starring: Christopher Nicholas Smith, Chloe Csengery, Jessica Tyler Brown, Lauren Bittner
Factual error: During the sleepover in the tent Dennis gives the girls M&Ms to snack on. If you look closely you can see one of the girls eating a blue M&M. These didn't hit the market until around 1995, a full 7 years after this movie takes place.
More trivia for Paranormal Activity 3