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.
Revealing mistake: When Diane is pulled back from the front door near the end of the movie, they use a stunt double, as you can see the stunt person scramble off to the right after the real Diane lands behind the stairs.
Suggested correction: You're close. They did use a stunt double but you don't see the double "scrambling off." The stunt double is barefoot and the person you see clearing the shot is wearing shoes. Most likely a stage hand helping the stunt double with the landing.
Stupidity: The family ask 3 so-called ghost experts into the house. After seeing flying objects in the kids' room, they are suitably impressed. But later on, the female expert is sleeping, one of the men is in the kitchen wanting to cook a steak, and the second man has his back to the monitors, his head buried in a crossword puzzle and he has headphones on with music on, so he can't see, hear or see what is going on.
Suggested correction: The only one acting stupid in this scene is the guy at the monitors. They have to eat and sleep sometime; if anything, having two people awake and one asleep at a time is the cautious route. The one guy goes into the kitchen to cook a steak, but the guy at the monitors, despite being told he'll be the only one watching them, doesn't put down his drawing or take off his headphones, depriving him of sight and sound.
Suggested correction: Diane could've bought a new headboard obviously.