(at around 51 mins) When Malcolm is trying to tell Megan and her kids about the ghosts and demon possessions, Becky is shown recording him with her cell phone. When the camera is in front of Megan you see the cell phone. But when the camera angle changes to looking over her shoulder at Malcolm, the cell phone disappears.
(at around 29 mins) When Malcolm is trying to break it off with Abigail in his bedroom, the pen in the doll's hand appears and disappears between shots.
In several scenes, the white camcorder that Malcolm, or any other character, uses handheld can easily record with either the LED screen closed or open - yet normally, the product would stop recording if you close the LCD panel while recording.
When Father Doug stabs the other father he's gone and doesn't appear on the floor when he falls down in the other shots.