Near the end after all Hell has broken loose the 2 girls run out of their rooms and Ann is wearing a 1 piece nightgown that is off white, when one of the men come back to tell them to get out of the house she is now wearing a 2 piece purple outfit (panties and top).
Charlie leaves the door just open when he enters the house to search for Arty, but in the next shot door behind him is closed. When he is running to the exit, it closes in front of him.
When Arty is going down the stairs at the beginning of the movie and the can is falling behind him, it obviously falls in front of him, but in the next shot it's still falling behind him.
Position of the saw cutting Henry doesn't match the position where it exits as shown.
When Hollister bends over to pick up a tissue from the water that was never seen being dropped in the water in the first place, and when he get's grabbed and pulled in, his position and face expression are obviously different indicating two separate shots.
The film depicts a Catholic priest of St. Luke's parish leading a witch burning in 1692, the year of the Salem witch burnings. But there were no Catholic colonies in New England in 1692. Catholics had little presence anywhere in the 17th century American colonies, apart from Maryland.
Obvious make-up on girl's leg to simulate that's it's been hurt while swimming which in process makes it look bigger than her other foot.
Obvious doll used when man is hanged in the elevator.
There is blood when Sturgess is dragged by the hand, but he wasn't hurt, just pulled away, so there would be no blood.
Obvious light in the house when Arty is in which can't be just from moonlight. Later in the movie it's shown that the house has electricity, but wouldn't the pair in the car see that the lights are on in the house and that there' someone in there? Instead, the house is shown as pitch black from outside. There is obvious and frequent use of lights in various shots throughout the movie which don't synchronize with the darkness of the house that's supposed to be simulated.
During the flashback to 1692, as Father Andrew is getting murdered, they show his feet are shown flailing about. Problem is the materials (e.g. neoprene) used in his sandals would not be invented for another 250 years.
(at around 1 min) During the flashback to 1692, as the witch is being raised on a pole to be drowned in the lake, one of the villagers raising the post is wearing a wrist watch.
(Around 51:00) During the execution of the witch, her modern dental work, including a row of amalgam fillings, is visible.
When the father is trying to escape the witch, he looks in to a mirror, and you can see the cameraman's face moments before the mirror explodes.
When Arty is hurled against the ceiling in the beginning, the rig holding him aloft is visible just before his head hits the ceiling in the long shot. The next shot is a closeup of his head and shoulders actually hitting, and the rig is gone.