When Josh and Dalton are swarmed by people in the Further and the electricity of the house begins to go out in the living world, we hear the bulbs shatter. However, some of the lights that go out are clearly candles or other non-glass things yet we still hear the sound effect for them.
When Elise first sees the demon, she describes him to Specs as having eyes that are "like two black holes," and has him draw a picture as such. Also, Dalton's picture of the demon is that of a red face and two completely dark spots for eyes. However, when the demon appears in person, his eyes have extremely constricted pupils, and at other times the eyes of a cat.
(at around 14 mins) At the beginning when Dalton falls, after trying to turn the light on, Josh runs up to go see if he is okay. When Josh is sitting on the couch playing with his newborn his shirt is untucked, unbuttoned, and he has no tie on. When Josh reaches Dalton to pick him up, his shirt is tucked, buttoned, and has a tie on.
(at around 27 mins) When Josh Lambert goes to the front door to investigate, he flips on the porch light, which blows immediately. Moments later, they show an exterior shot of the house with the porch light on and no explanation as to how it was replaced.
(at around 28 mins) When the alarm goes off and Josh runs downstairs the front door is wide open and the porch beyond with no screen-door, something that was present earlier when he opened the door to look outside after the knocking. After he has gone around the house checking everything out and the alarm goes off again he closes the front door. The next scene is an exterior shot of the house and there is clearly a screen door present again.
(at around 52 mins) The first time Elise and her crew enter Dalton's room, the light switch just inside the door is a regular Decora® on/off switch. When they later set up to try to communicate with Dalton in his room (at around 1h 1 min), the light switch has changed to a circular dimmer switch, presumably to serve Elise's line to dim the lights.
(at around 1h 22 mins) When Josh Lambert is walking towards the red door, up in the attic in the dream world (spirit realm), a dimly lit man can be seen moving about and pumping fog out of a fog machine in the bottom left side of the screen.
(at around 19 mins) When Josh Lambert is upstairs in Dalton's room, he goes to the dresser drawer to grab clothes for Dalton. When he bends down to grab the clothes, you can clearly see his microphone cords.
(at around 1h 6 mins) When Elise and Specs are performing their astral projection and communicating with the demon, there is a man with a handheld video camera walking around behind the cast. This is the other member of Elise's crew (the one with the beard) who is filming. Only four are seated at the table during the communication.
The goof item below may give away important plot points.
(at around 1h 21 mins) When Josh is in the old house while in the Further, the seated family is killed by a woman holding a M1 carbine, a semi automatic rifle, while the sound of the firearm is of a manually loaded weapon, more so resembling the sound of a bolt action rifle or pump action shotgun cycling the action.