Factual error: During the opening scene in 1988, a silver TV from the late 90's/early 00's is in the living room/dining room area. (00:02:10)
Factual error: Eddie specifically tells the gang not to take his mom's "Delicious Deals" snacks because his mom loves them. But Delicious Deals are made by Mrs. Freshley, a company that was not founded until 1994. The boxes used in the movie even include the modern design that can be found today in most Dollar Tree stores. (00:23:00)
Factual error: When Stanley is at synagogue practicing for his Bar Mitzvah, and the Rabbi tells him to close the book, he does so - and a clear shot of the book cover from Stanley's left shows that the book (in Hebrew) is upside down. Hebrew books read right to left - the cover should be on Stanley's right, right side up.
Factual error: Police cars are shown with red and blue lights. Police cars in Maine only display blue lights.
Factual error: Bill is holding a Lego turtle and drops it on the floor, then you see a closeup on the parts. Green Lego bricks were not commercially available before 1996 and lime green Lego was not available before 2003. (00:56:20)
Factual error: When passing under the railway bridge not only are the cars modern but there is also a Canadian Tire container on it which is a Canada only store, and doesn't ship by rail in the USA.
Factual error: When Bill meets Beverly for the first time and the shot is showing her while walking towards the other guys, some modern SUV are visible in the background.
Factual error: Ben's headphones look like 1995 plastic models and not 1989 style.