After Meghan falls down the stairs, Abby yanks the end of the trip-wire off its metal screw-eye, but the eye remains in place, still fastened into the wall. Yet nobody notices it afterward, and then later when Meghan looks in the pocket of Abby's jeans and finds the rolled-up wire, the screw-eye is again attached to it.
Carter's cell phone at the end of the movie (when ringing in the car) is not the same one he had in the beginning.
The neighbour misspells 'Abby' in her second internet search.
There are numerous inconsistencies with the struggle when Abby is stabbed.
When sitter is stabbed in back you can see cardboard under her shirt to hold knife there.
The bogus article seen on cork-board at the start of the film has a subtitle with the word "private" misspelled as "privet." The article itself has nothing to do with the headline, but is a description of the position of a chairman of a company's board.
As Abby walks up to the house and is introduced to the neighbors, the right arm of a crew member can be seen behind the tree across the street.