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."
Continuity mistake: When the creature rips out Elizabeth's heart, Elizabeth's head is originally turned to the side. When they cut back her head is facing forward.
Continuity mistake: When the medical examiner notices that there's something wrong with the brain of the corpse that she is examining, she's making a gesture with her hands but in the next shot she has them by her sides. (00:30:39)
Continuity mistake: Constantine drives to where Beroul had teleported Chas, and Chas angrily gets into the car and slams the door shut. He does not put on his seatbelt and places his hands on the steering wheel before lowering his head a bit. It cuts to a close up before he turns to look at Constantine again, and suddenly he has his seatbelt on. (00:35:40)
Visible crew/equipment: When Diane and Steve go to their neighbor's house after the scene of the chair sliding across the floor, there's a flash of lightning that reveals a shadow of a fan that's blowing on the actors on the left side of the house.
Visible crew/equipment: When Skip has just finished snorting cocaine and is talking to Stella, the boom microphone is visible on the top left of the screen.
Continuity mistake: When Ellie falls from the tree after the rope from the tyre breaks, Louis runs with his wife to see how she is. Louis is wearing a plain white crewneck T-shirt with the sleeves rolled up. When Rachael yells "Gage!", you now see Louis wearing a striped white unbuttoned collared shirt and sunglasses. When Louis is running for Gage, he's back to his plain white T-shirt with the sleeves rolled up. (00:05:40)
Visible crew/equipment: When Dmitri gets weapons from the back of the government vehicle: you can see the reflection of 3 crew members in the window of the truck. In the same shot you can see a crew member's gloved hand holding a flashlight inside the vehicle to light the scene. (01:16:00)
Revealing mistake: Just after the scene where Mark is killed, there's a shot of Jason's feet as he opens a screen door and walks across a dusty hardwood floor. As the dolly pulls backward across the floor, you can see the camera's roller marks in the dust. (00:59:10)
Continuity mistake: During the chase scene where they attach the "engine killer" remote to the Dodge M4S (aka Wraith's vehicle), 2 Chevy Malibu Cop cars are barreling up the road towards the racers. Once the cops pass the starting line, the cars are now Dodge cop cars. (00:44:25)
Continuity mistake: After Jen shoots Stan in the shoulder, she stands back up and looks through the eyepiece of her shotgun. The petrol can Stan was using to fill the SUV with is on the ground beside the right rear tire. When Jen walks up to the SUV, the can is now behind the car. (01:16:50)
Continuity mistake: When Casey and Delilah watch Nurse Harper get infected by Coach Willis from inside a closet, the closet's shutter windows switch from closed to open between shots.
Continuity mistake: When Lucy comes home at the beginning of the movie she quickly buttons the top of her dress. While eating dinner, it is open and then buttoned again between shots.
Continuity mistake: Towards the end, right after Mia crawls through the tunnel and into the shed, she backs up against some shelves. There is a lot of blood on her face and her hair is hanging over her face. The shot changes to a close-up and her face now has much less blood on it and the hair that was hanging in her face is gone. (01:16:25)
Continuity mistake: After Chloe runs off into the woods and the other two girls finally find her after she's had her run in with Slender Man, they are shining the flashlight in her eyes and asking her questions. In one shot her eyes are still open as she gazes near blankly off in the distance. When it cuts to a close up and suddenly her eyes are tightly squinted shut. (00:38:45)
Visible crew/equipment: When Fred and Bertha are walking together near the end, when Fred says, "I don't really think there's a future there," and Bertha replies with, "No?" the film crew is reflected in Bertha's sunglasses. (01:18:46)
Continuity mistake: Gina's father opens the door, club in his hand, and finds his family inside for the surprise party. In the reverse shot, Gina's position is also mirrored, having the right arm raised instead of her left. (00:08:15)
Continuity mistake: Andy returns home a little early and opens the door finding mom doing tonsil hockey with a dude named Shane. The multicolored wrapping in her hand switches instantly from right to left hand as she realises her kid is there. (00:09:20)
Continuity mistake: Lady Raven arrives at the Coopers' place and starts talking to the wife. Cooper's watch is set to 1:35. An instant cut later it's set to 1:20.
Continuity mistake: When Tyler injects Brigitte for the first time at the hospital, look carefully at the syringe. You'll see that in the first shot its content is 1/3, and in the following shot is now 1/2 full.