Most of the scenes in the trailers are not in the actual movie which angered many fans of the series. According to Inside Pulse, the production team behind this had enough leftover footage to assemble two completely different versions of the same movie; fifty-percent of the footage was what they used to create the TV spots and theatrical trailer.
(at around 5 mins) Towards the beginning of the film, Julie takes a picture of young Katie standing in the driveway shortly before a group picture is taken. The photo being taken appears in both Paranormal Activity (2007) and Paranormal Activity 2 (2010) as an indication that the demon has started haunting them.
(at around 4 mins) The scene with Kristi's loose tooth was real. "Little girl shows up on set and says that she's got a loose tooth," Ariel Schulman said. "We say, 'Film it, work it into the scene.' Can't fake that."
Very little set dressing was done on the house from Paranormal Activity 3: "We would walk into [some of the potential locations] and it would be like they were frozen in the 80s," said Peli. "We wouldn't even need to do too much to them. So, sometimes you get lucky. [...] We didn't want to throw the 80s thing in your face too much. We didn't want it to make it hugely like, 'Look, it's the 80s!"
The highest grossing film in the Paranormal Activity series.