Continuity mistake: In the first movie the "Welcome to Silent Hill" sign is on the right. In this movie it's on the left.
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.
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)
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.
Continuity mistake: The man with one arm in the projector slides shows his right arm removed below the elbow. The next slide shows his left arm missing, and then it goes back to his right. (00:35:34)
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.
Continuity mistake: In the underground lab, Dr. Su offers to surgically remove the false memories he implanted in John's brain. He drills a half-inch hole in the right side of John's forehead, which leaves the right side of his face covered in flowing blood. John can't stand the pain, breaks free, and he goes on a rampage throughout the underground bunker, killing every UniSol in his path. As he fights his way through the bunker, the bleeding hole in John's head switches from the right side of his forehead to the left side, then back to the right side again. Also, in the last scene (an unspecified amount of time after the bunker brawl), John has no scar on his forehead at all.