Plot hole: The motivation of the cult in this film - a dark entity trying to birth their demonic god - is completely different from the cult of the original film, which was portrayed as fanatical Christian witch-burners. No satisfactory explanation is given in the film to explain this and in fact the film explicitly implies they are the same cult on several occasions. The explanation that the cult of the original film is some sort of offshoot or different sect of the cult from this film cannot explain this as it is pure fan speculation and conjecture (thus non-canonical) and in fact raises several more plot-holes.
Other mistake: The caption onscreen when the C.I.A. Headquarters are shown reads "Langely, Virginia". It should be Langley. [Might be Netflix only].
Factual error: In the beginning scene in the locker room, Taylor brings up his Glock and calls it the "Glock 19", however a shot shows the pistol's trademarks, displaying it as a Glock 22.
Revealing mistake: When Picasso removes the first finger from Fan Yau Lee's hand, you can see that there is no blood on the instrument used.
Factual error: When the main character goes into the church, she looks at a picture from 1989 labeled "annual picnic". In the picture a boy (next to the main character's mother) wears a hat with a DC (DC Shoes) logo on it. DC Shoes was established in 1993. (01:00:00)
Continuity mistake: After John's tracking device is removed there is blood on the back of his T-shirt. The amount of blood varies from when he gets on the boat until he gets to the underground shelter.
Character mistake: When Michael goes to the antique shop, the sign out front is spelled wrong; it reads "anitques."
Plot hole: The killer has been living in the (apparently big enough) crawlspace between walls and floors, for over a decade. There is no explanation (or rationale) given on how he moved the various objects inside every room, closed doors, fed when the house was not occupied, hid the various corpses and, silly detail, concealed his own BO and the stench of his own living quarters, which is something hinted at when they find out his hideout. It is explicitly said that he is agoraphobic and does not get out, ever.
Continuity mistake: When Sheriff Cooper writes "Karsson" and underlines it on the chalkboard, the way it is written changes between shots. In one particular shot, the line he underlined it with is suddenly rubbed out.