Visible crew/equipment: During the beginning of the film whilst Tara is walking through the house, in the window to the right of the front door the camera guy can be seen during both scenes that take place during the hallway shots.
Visible crew/equipment: When Mia first does the ritual, you can see the boom mic on the bottom right corner. It hides in the dark corner, but if you look carefully, you can see it come in the shot. It's easier to, depending on how dark your screen is. (00:20:40)
Factual error: The teacher sends her pupils to the woods to collect chestnuts. Later we learn that the date when all this happened is May 30th. Chestnuts ripen in autumn, around September-October. (00:52:18 - 01:05:06)
Continuity mistake: Before taking Michael's mask, Corey calls Allyson and tells her to meet him at the diner at 9:00 pm. Later we see Allyson at the diner waiting for Corey, but when she checks her phone and sees Laurie is calling the time is 5:36 pm. (01:13:56 - 01:24:41)
Revealing mistake: The very first shot of the movie, supposedly of Anya Taylor-Joy lighting a cigarette, does not match the following shot on the pier; the cigarette appears to be black and with a brand sleeve instead of the normal one she is smoking. The background confusingly looks more like an interior than the pier she is standing on, and the lighter is a common Bic-style one instead of the Zippo she is using also later in the movie. That's because it's actually stock footage. You can literally find the clip yourself on Shutterstock and similar websites, by the description "Close-up of the silhouette of a woman's face sticking a cigarette into her lips, igniting her with a lighter, and exhaling smoke. The grim concept of the harm of smoking in a low key." (00:01:00)
Continuity mistake: RJ got into his van and drove parallel to the house, almost reaching the end (right side) of the house when he saw Pearl in front of him and stopped. When RJ got out of his van, it was parked near the beginning (left side) of the house that he had already driven past. Also, Pearl was standing in front of a fence, so it didn't make sense that RJ would be driving straight toward a dead-end. (00:57:07)
Character mistake: Laura is on the floor, screaming and exhibiting bizarre behaviour, so Dr. Rose Cotter goes to the wall phone to call for help. Instead of maintaining observation and continuing an evaluation of Laura, the psychiatrist faces the wall while making the call and even stares at the wall for a couple of seconds after hanging up. A patient's body language can/do help make a diagnosis, so the psychiatrist should keep her eyes on Laura. (00:11:20)
Continuity mistake: After Ross is shot, he lies on the pavement with his head to the left of the white line, but later his head is to the right of the white line. (His body would not be rotated 180° by police.) His head is on the white line in between this discrepancy. (00:06:38 - 00:09:30)
Plot hole: Mike carried Sophie into the hospital and walked through the halls yelling, "I need a doctor" until he ran into Sophie's Dr. Thomas. Sophie was put on a cot and rolled into a room where Dr. Thomas immediately began examining her. Mike completely by-passed registration, triage, etc, which wouldn't be tolerated at an emergency room. Emergency rooms are highly likely/almost always back-logged with patients, many with urgent conditions yet still might wait hours to be seen by a doctor or nurse. (00:06:45 - 00:07:20)
Continuity mistake: The car behind Julius is at various distances. It is closer when the camera is on Julius than when it switches (back and forth) to his passenger, Margot. (00:02:39)
Continuity mistake: When Maren first sees Lee, she finishes putting some small tampon boxes in her bag. She has her right hand on her bag, but when the shot cuts, her right hand is against the shelf. (00:33:15)
Continuity mistake: The piece of paper that had "MIN" written on it suddenly changed from being in the corner of the table to being on the left side of the planchette (heart-shaped pointer), which was near the center of the Ouija board and table. (00:10:20)
Deliberate mistake: After Sam freed Gary from being tied up by the aliens, Gary pulled off the cast he got earlier that day and was able to use his left arm as though it had never been broken. (00:45:43)
Continuity mistake: Before Eamon hung his jacket and hat on the nails, there were three nails close together near the right side of the board. When he was hanging his jacket and hat, there were only two nails, which appeared to have more distance between them. When the camera shifted, there were a couple nails protruding to the left of the hat. The single nail that was on the far left side of the board turned into two nails. (00:04:38)
Continuity mistake: Solomon put the rope around his waist underneath his coat, but when he was walking through the woods the rope was tied over his coat. Also, the knot would start out in the front of his left side but change to behind his back even though the rope was loose (not taut) behind him. (00:01:55 - 00:02:26)
Revealing mistake: A white truck could be seen in Tamra's rear window, following her car at varying distances. After Tamra hit Randall on his bike, the white truck was still there but gone when the camera returned to a front view of Tamra. Use of a green screen - the truck could not have gone past the accident or "disappeared." (00:03:35 - 00:04:10)
Continuity mistake: When Harry wrapped Lily's ankle injury, there was bloody wrapping below the duct tape. When Karl asked to see Lily's leg, there was no blood showing on the material below the tape. Also, Harry did not completely cover the ankle injury with duct tape like he did to keep creatures from smelling the blood on Lily's stomach cut, questioning why the creatures could not smell the blood on Lily's ankle. (00:19:55 - 00:26:50)
Continuity mistake: Ava sees the stack of mail on the table. She sweeps her hand (fingertips and envelopes are off-screen), as she slides the top envelope closer. Ava picks up the top envelope, as if her hand sweep does not move any of the envelopes (and serves no purpose). (00:05:48)
Continuity mistake: As the SUV pulls off alongside the curb, there are trees with orange-coloured leaves on both sides, but the leaves are green when the ladies are talking in the stopped SUV. The leaves from the tree that is about 15' from the curb are right outside the passenger-side windows. (00:10:15)
Continuity mistake: Jenna takes one red cup from the 3 stacked next to the higher stack and returns the two cups to her left (and left of the higher stack). Jenna uses her left hand, supported by her right, to handle the bottle of wine, but the 2 cups disappear after she sets the bottle on the table. (00:19:50 - 00:20:14)