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)
Continuity mistake: When Eddie falls through the floorboards, you can see his arm looks perfectly fine and is unbroken in a few quick shots. After the movie cuts back to him a few moments later, suddenly his arm is badly broken. (01:20:30 - 01:23:25)
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)
Suggested correction: There were several TVs similar to the one pictured in 1988. A quick Google search of "TV's available in 1988" will tell you this. Without knowing the manufacturer or model of the TV, you cannot state this as a movie mistake. If it was a LCD TV in 1988 then yes but, this one, no you can't assume this TV was not available.
Continuity mistake: In the beginning of the movie when Georgie is running down the street chasing the paper boat his walkie-talkie is in his right raincoat pocket. After running a bit it switches to his left pocket.
Factual error: At the pharmacy on the shelf is Olay. It wasn't called that until 1999. It was Oil of Olay in 1989. (00:37:30)
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: Nivea Soft Cream is on the shelves at the chemist - this did not exist in 1989, when the film is set.
Suggested correction: I think the date is subject to debate. The only thing we really have to go on is it's 2019 in chapter 2, and It comes back every 27 years which would be 1992.
The date is not subject to debate. The marquee on the movie theater is advertising both "Batman" and "Lethal Weapon 2," placing the movie in the summer of 1989.
There is no debate about the date. After the title card it says "June 1989." The opening scene took place "October 1988."
Factual error: Police cars are shown with red and blue lights. Police cars in Maine only display blue lights.
Continuity mistake: When Beverly kisses Bill, in one angle his ear is between her fingers, from another her entire hand is on his cheek. The blood smear she leaves behind also changes. (02:08:20)
Continuity mistake: When Beverly is in the bathroom she puts out her cigarette on the cubicle wall using her right hand. The shot switches to overhead and she's now using her left. (00:12:10)
Continuity mistake: During the rock war, there's a slow motion shot of Belch screaming before Beverly then throws a rock at him. In the next shot of Belch, there is suddenly a cut on his nose before he ever gets hit. (01:06:50)
Continuity mistake: As Georgie is chanting at Bill "You'll float too! You'll float too!", Pennywise rises up from the water with crossed eyes whispering and wet hair down around his head and face. It cuts to a wide shot and now his eyes are normal, and his hair is parted and pushed back, while being less wet. (00:59:10)
Factual error: During the rock fight, Richie calls Henry Bowers a "mullet wearing a**hole." The term "mullet" wasn't coined until 1994 by the Beastie Boys in the song "Mullet Head." (01:07:15)
Continuity mistake: The glass Bill uses to cut everyone's hands doesn't stay bloody for each character despite him never wiping it off. (02:05:05)
Continuity mistake: When Beverly is signing Ben's year book she has the pen lid in her mouth. It disappears and then reappears.
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 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.
Continuity mistake: At the quarry, there is an amusing scene where the boys all ogle Beverly. When she turns to look at them, they all pretend like they weren't staring at her. Pay attention to Richie during the next four shots. Richie looks to his right twice between the first two shots, and his legs go from crossed to uncrossed between the third and fourth shots.
Continuity mistake: Early in the film, Georgie draws a smiling face into the misted window in Bill's bedroom. When Georgie turns around to approach his brother Bill, the condensation and smiling face are gone. As the scene concludes, we see a close-up of the smiling face again, fading off the bedroom window. (00:01:00 - 00:03:00)
Continuity mistake: As Leroy is talking to Mike about his future, Leroy points to the animal pen with his left hand, but the shot from Leroy's rear shows him pointing with his right hand.
