Revealing mistake: When the chair moves across the kitchen floor, Craig T. Nelson goes to investigate it (after it has stopped moving). He goes up to the chair and flips it over. If you look closely, Craig almost hits the camera with the chair's legs. You can tell this has happened because the camera moves up very quickly and Craig looks straight at the camera crew with very big guilty eyes. This is more easily visible on the widescreen version of the film.
Continuity mistake: Likewise, when Carol Anne is being sucked into the closet vortex she clearly lets go of the white wicker headboard of her bed. In the next shot, the child (actually a dummy or a stunt double) is seen sailing into the closet, grasping a sizeable section of the now broken headboard.
Visible crew/equipment: In the breakfast scene when Robbie's milk glass spontaneously shatters from the bottom. Watch closely, you can see a string coming out of his cereal bowl and attaching to the bottom of his glass. Robbie just needs to give the glass a little tug, and splash. Watch in slo-mo a couple times, then it's really obvious at regular speed.
Continuity mistake: In the opening sequence while the kids are in bed, the toys on Robbie's headboard keep changing. The Rams football helmet is always there, but next to it, you will see a Star Wars droid, a Rubik's cube, a race car, or a dinosaur, depending on which shot it is.
Revealing mistake: When the father tucks Robbie in and Robbie says "I don't like the tree, dad." the camera shot begins rolling to the left. Robbie flinches when reacting to someone telling him to lean back more so he's not blocking too much of the father's face. The father also improvs a solution by gently pushing Robbie's shoulder back a bit as well.
Visible crew/equipment: Near the end of the film, when she lands behind the stairs. If you look in the right hand corner, underneath the stairs, you can see tennis shoes running by.
Continuity mistake: When the men are watching football, they are reacting as if they are watching live action. However, the images shown on the TV are clearly in slo-motion.
Continuity mistake: As Diane brings the freshly-washed flask to Dr. Lesh, who's sitting at the kitchen table, the flask jumps from one hand to another.
Continuity mistake: The wicker headboard of Carol Anne's bed is ripped apart when she holds onto it to try to keep from flying into the closet. Towards the end of the movie, when her mom tucks her into bed,the headboard is intact and has had no repairs.
Visible crew/equipment: Near the end of the movie, when Diane falls down the stairs and runs towards the door, she grabs the door knob. When she gets thrown backwards, you can see the cable that is attached to her shirt, pulling her back, in the first couple of frames in slo-mo.
Continuity mistake: At the start of the film, the dog is seen going from room to room looking for food. Just before he goes into Dana's room, someone can be seen through the crack in the door, moving from left to right.