Character mistake: At the hospital, the inspector manages to get from the nurse the file of the patient with the liver condition. Forgetting the fact that the Turin, Italy hospital is using English for its documents (it's simply a cinematic convention), the problem is that the letterhead of this document says "Department of Chronic Deseases", misspelling the word.
Character mistake: When they're making the protection circle they make a star of David and not a pentagram, 6 points in a star vs 5 points.
Suggested correction: I don't think there was anything in the movie that dictated a pentagram had to be used. In the book of protection rituals they were using, the particular ritual showed a picture of the star of David they needed to create, so that's what they used (plus salt).
To add to the correction, what the mistake refers to as "Star of David" is a hexagram and the use of hexagrams in the occult are not uncommon. You can find salt protection circles that use the hexagram.
Character mistake: Given how smart the lead is he doesn't seem to know the proper dosage of sleeping meds he put into his mother's coffee. He placed in enough to possibly cause an overdose.
Character mistake: The ref says there's no rules before McClure fights Whiplash but she tries stopping them later.
Character mistake: There are signs out front as the Spenglers arrive at the dirt farm. One of the signs is a call back to a scene in Ghostbusters 1984. In the scene, Ray quotes the book of Revelation: "And I looked, and he opened the sixth seal, and lo, there was a great earthquake. And the sun turned black as sack cloth, and the moon turned blood." When Finn Wolfhard reads it he misquotes the line saying "The sun became as black as cloth."
Character mistake: Near the end while in the caves Maggie is the first to go missing, but they use the name Gwen multiple times, the actress' actual name.
Suggested correction: Maggie Q is the actress and she plays the character Gwen Olsen.
Character mistake: Andy speaks of Billy changing in the two months after he was hired when he was hired in the spring months ago.
Character mistake: Zeke makes the bold claim that "John Kramer didn't target cops." This is completely and utterly false, and a cop like him should know better. Kramer repeatedly targeted cops. In fact, both "Saw II" and "Saw IV" have officers (Detective Mathews and SWAT Commander Rigg) as Kramer's main target.
Character mistake: John shot at the "werewolf" but wasn't successful in hitting it. Instead of pursuing the werewolf, who he supposedly was determined to catch, he let it run away. Alcoholic or not, a sheriff's deputy should have done everything possible to try to capture the creature that was terrorizing the small town. By not even attempting to follow the werewolf, John missed the one opportunity he - or anyone else - had thus far to potentially put an end to the senseless and tragic murders of young ladies. (00:55:35)
Suggested correction: Dude's daughter was attacked and bleeding from the head, of course he didn't pursue it.
Suggested correction: He didn't go after the wolf because his daughter was hurt, and his (albeit misguided) parental instincts took over. It's not at all a character mistake for him to prioritize making sure his daughter is all right over chasing a perp. Most parents would probably do the same thing.
Character mistake: When searching the database for the missing girl, they find her and it says missing since 7 January 2021. When Caleb read it, he says "missing since February..."
Character mistake: The very advanced computer on the plane can't spell, since it infers probabilities that a member of the crew has been "INFECTETED" by the creature. (01:06:40)
Character mistake: When Modoc is suggesting what type of blood to drink, he suggests pigs blood B-. Swine don't have B blood. They have A and O blood only.
Character mistake: When Joan is searching the web looking for information on what monkeys eat, there is a section on the screen that reads "The diet of monkeys varies form fruits, leaves." Obviously the correct word for this sentence should be "from" not "form." (00:36:21)
Character mistake: A detective (Briggs?) told Sonny, " that I was stupid enough to believe your dark fantasy NINE-ELEVEN call." [emphasis added] An American law enforcement officer, in particular, should know and use "nine-one-one" (911) when referring to the nationwide emergency telephone number. "Nine-eleven" (written 9/11 and NOT 911) is used to refer to the September eleventh (9/11/01) terrorist attacks in the U.S. (01:15:57)
Character mistake: The prosecuting attorney told William, "In the interests of getting this thug [Danny] off the streets as soon as possible, his attorney has agreed to plead guilty to assaulting an officer, possession with the intent to distribute, and resisting arrest, and that's all in addition to his parole violations. We're looking at five to seven [years in prison]." The parole violations alone are sufficient to get Danny off the streets immediately. (00:09:34)
Character mistake: In the very beginning at the baseball game the runner is running to second base and the fielder doesn't even try to tag him out. Just runs right by him and gets the ball to the pitcher. (00:00:53)
Suggested correction: The center fielder missed the ball and the right fielder got it. The second baseman was at the border of the infield and outfield and the right fielder may not have noticed that the short stop moved to cover second base. By this time, the players might have been more concerned over the opposing team scoring a run because a player had advanced to third base. It was a "revealing" mistake or overall "stupidity" by the team as each player was playing "musical positions" more so than good baseball.
With regard to "revealing", the players may have been instructed to be active on the field and cover bases for each other as needed and this was the "mess" they produced.
Suggested correction: Baseball players make mental errors all the time, even major leaguers.
I've watched the scene a few times and can't agree or disagree with the mistake, but it certainly doesn't look like a mental error one would see in a game, even a little league game. It just looked like two kids were given directions what to do and the timing might have been off and the director on set didn't bother changing it. (I'm not disagreeing or agreeing with the correction either, just making a statement to help others decide).
Character mistake: We see the lead driving on the motorway to get to the cottage. She leaves at junction 6 for Princes Risborough. Which means she is on the M40 that goes to Birmingham. When she arrives the host asks about the drive down and mentions the M4. This is a different road entirely, that goes to Swansea.
Character mistake: Mia's Sea-Monkey, in a vertical position, was shown sinking to the bottom the jar. It isn't clear if the Sea-Monkey was dead or if Mia was referring to it when she said, "She's gonna freeze to death, Aiden", but Mia should have known how to properly care for her Sea-Monkey (or refer to the instructions) and, realizing the room was too cold, should have done something - such as wrapped a towel/blanket around the jar and/or moved the jar to a warmer location (e.g, near the fireplace). (01:22:33)
Character mistake: The Predator is jumping through trees, then landing in a creek, splashing in the water. Its cloak barely flashes for a moment, then it can walk through the water still cloaked. This is a prequel to the other Predator movies, where it is already established that with their cloaking technology, even in the future, walking in water or getting wet disrupts the cloak and it malfunctions. (00:37:10)
Character mistake: Nolan said, "Everybody knows that no sharks swim in freshwater" and Spencer said, "They don't come into freshwater", but there are freshwater sharks (e.g, river sharks) and bull sharks (not true freshwater sharks) can survive in saltwater or freshwater. Jacob Harper (National Aquarium) pointed out eyewitness accounts of sharks swimming up the Mississippi River and "bull sharks have kidneys that recycle salt" but did not mention the glands near their tails that help keep salt in their bodies. (00:08:08 - 00:29:50)