Revealing mistake: When Diane bends down under the sink during the famous chairs on the table scene you can see the large potted plant on the other side of the counter shake, obviously one of the crew members trying to get down under the counter before the camera switched back to the table.
Audio problem: When Carol Anne says "they're here" her mouth doesn't match the words.
Revealing mistake: Diane runs back from the neighbor's house and falls into the pool. You can see where she is going to fall and she runs right to that spot. It looks like they did multiple takes.
Visible crew/equipment: When E. Buzz is heading for Dana's door, someone wearing blue jeans and a red shirt can be seen briefly in the doorway. (00:02:02)
Continuity mistake: When Robbie throws his jacket to cover the clown, he throws it effortlessly and misses by far; one can even notice he throws it quite low. Shot changes and the jacket is flying high at a bigger speed.
Continuity mistake: Before the clown attacks him, Robbie stretches his right arm and turns the light off. A shot later his right arm is resting by his side, and he is lowering his left arm.
Continuity mistake: When Carol Ann is in the kitchen while her mom is doing the chair demonstration she is holding up a toy with her left hand and helmet in the right hand. When chair slides across the kitchen floor a close up shows Carol Ann yawning then immediately back to her holding the items. Clearly they inserted the yawn scene in as an after thought.
Continuity mistake: The window in Robbie and Carol Ann's room never has a mini blind. After the tree breaks through the window and the family races up to their room the window is intact with a blind in it. (00:39:00)
Revealing mistake: When Diane is on the ceiling, a piece of something white falls right in front of her, landing on the ceiling. This shows the set was upside down and she was actually on the floor. The scene was shot on a rotating stage but the little piece that falls gives away the effect.
Visible crew/equipment: Near the end when Diane is reaching for the kids and trying to get them out to the hallway, a film light is blatantly visible behind her. Also during the same scene the shadow of a fan can be seen in the hallway.
Continuity mistake: When the parapsychologists are attempting to record Carol Anne through the TV set, Ryan's hands are by his headphones, but the next shot shows him move his hands to his headphones again.
Continuity mistake: When Steve Freeling is in the living room with the Ghostbusters, he has a cigarette behind his ear. In another shot seconds later it disappears then reappears again.
Factual error: Robbie is grabbed by the big, gnarly tree outside his bedroom window during a severe thunderstorm, and Steve rushes outside to save the boy as a full-blown tornado passes overhead. The tornado sucks up the tree (which certainly weighs several tons); yet, completely defying physics, Steve and Robbie remain unaffected by the powerful updraft, even though the two are directly beneath the tornado vortex.
Answer: Ectoplasm.
Phixius ★