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: 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: Tyler said, "Charlie says you're [Ben] gonna tell your folks that you got that girl pregnant this weekend." "This weekend" is a misplaced modifier. Ben didn't get the girl pregnant this weekend; Ben is supposed to tell his folks this weekend that he got a girl pregnant. (00:22:15)
Character mistake: The crew deride Garrett's title of Flight Officer, claiming that she can't have it because she hasn't flown in combat. In fact, Flight Officer was a genuine WAAF rank corresponding to Flight Lieutenant. Many RAF officers holding the ranks of Flight Lieutenant, Flying Officer, and Pilot Officer were not aircrew, despite their titles.