Factual error: The idea that anyone survived living long term in Pripyat Hospital is absurd. At the time the film was set the hospital was still radioactive and prolonged exposure by living there would be fatal. Nobody could survive on the grounds for more than two or three months without receiving a lethal dose of radioactivity. Incidentally, prolonged exposure to radioactivity doesn't turn you into a deranged zombie - it turns you into a corpse.
Factual error: The type of surgery shown made by the machine transversely cuts the rectus abdominis muscles. Besides not being a standard surgical incision in order to "remove a foreign body" as stated, it seriously damages important muscles of the abdominal wall making any immediate active mobilization of the trunk virtually impossible, even under strong analgesia.
Factual error: In the scene where Arthur first enters the house and starts going through paperwork, there's a shot of Nathaniel Drablow's death certificate which shows 'body was not recovered' in the box next to his cause of death. Such a thing would not be written on death certificates of the time - that box is reserved for 'Signature, description and residence of informant', a heading which can partially be seen as the camera pans across the certificate. For the death to have been registered, an informant's signature would have to have been there. (00:20:05)
Continuity mistake: Just before Steve Hadley is killed by the Merman, his tie is wrapped around his neck. When the Merman attacks him, his tie is worn properly. (01:19:40)
Continuity mistake: In the first movie the "Welcome to Silent Hill" sign is on the right. In this movie it's on the left.
Factual error: At the start of the war, it says Fort Sumter 1861. However, on the battlefield we see the US flag with 35 stars. In April 1861, there were only 33 states.
Continuity mistake: When Alice knocks over the giant Licker in the Rolls-Royce, the driver's side of the car remains completely undamaged. Unlikely, but for the rest of the chase there are four giant scratches across the rear of the car. (00:51:10 - 00:52:05)
Continuity mistake: When Alex and her boyfriend are going up to the play gym, her hair style changes. It's crimped as they are walking up, then changes to straight when they are taking Hunter home.
Revealing mistake: Right at the end of the fight between Selene and the Uber-Lycan in the vampire coven, the Uber-Lycan throws Selene into some wooden panels, knocking her unconscious. As she travels through the air you can tell that she is suspended by wires; she travels far too slowly towards the wooden panels for someone who was just thrown. (00:48:35)
Revealing mistake: When Sparky's tail pops off there is a hole where it popped off. But when the tail goes into the bucket the hole is gone.
Continuity mistake: Laura is trying to protect Taylor and his sister from the zombies and holds a baseball bat. It shows her dead zombie husband approaching her and then shows a split screen view of them both. Behind Laura, you can see Taylor on her right side, left of the screen. It then cuts to show her about to charge John and yelling, and suddenly Taylor is on the other side. (00:02:15)
Continuity mistake: At the battle of the bands Ryan's car is smashed by Tyler and his friends, specifically the windscreen and headlights. When Elissa drives the car minute later, it is in perfect condition. It's also in perfect condition when Ryan later reverses it into the garage.
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)
Deliberate mistake: Nearly every night scene inside the house is lit by very bright lights shining in the windows from outside. Yet every time anyone is outside the house, it's still just as dark. There is no light source from which these lights could possibly originate.
Audio problem: When Emily picks up the tooth from the box, she says "ew" but if you look in the mirror her lips don't move.
Factual error: When the underground garage of the market is flooded, the car that Kyle and Heather are in does not flood. A car is not water tight like a submarine. Even though the water does not cover the top of the car, water would flood the entire car within minutes.
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.
Other mistake: After the daughter visited with her mother for the first time, she is reviewing the footage with the priests. No such camera angles were taken for what they reviewed, only an overhead room camera would have been available.
Revealing mistake: When Three Finger is driving the truck to ram the car containing Angela's husband you can see round the eyes that it is a mask being worn.
Character mistake: When Michael goes to the antique shop, the sign out front is spelled wrong; it reads "anitques."