* CowboyBebopAtHisComputer: The Creator/{{Netflix}} description of ''3'' says it is a sequel instead of a ''prequel'' to the series, and that ''4'' takes place five years after ''3'' instead of ''2''.
** Writers of quite a few synopsis/reviews/articles seem to believe that the malevolent entity in the films is a ghost, rather than a demon.
* TheDanza: Everyone in the first film. The characters Katie Featherston and Micah Sloat share their names with the actors playing them, while "Amber" is played by Amber Armstrong and "Dr. Fredrichs" is played by Mark Fredrichs.
* DuelingMovies:
** The first movie went up against ''Film/SawVI'', in a case of two subgenres of horror duking it out. Its resounding victory at the box office, despite playing in fewer theaters, is often regarded as [[GenreKiller the death knell]] for the TorturePorn genre that the ''Franchise/{{Saw}}'' franchise [[TropeCodifier served as the face of]], precipitating the rise of supernatural horror in the '10s. The second film going up against, and beating, ''Film/Saw3D'' the following year merely finished the job.
** The first film also dueled with ''Film/TheFourthKind'', another found-footage, supernatural-leaning horror movie released in the fall of 2009 (even if the baddies in ''The Fourth Kind'' were aliens instead of ghosts or demons).
* EnforcedMethodActing: Much of the dialogue for the first film was unscripted, with Katie Featherston and Micah Sloat [[{{Improv}} improvising most of it]]. Also, in some scenes, they weren't told when anything scary was about to happen in order to get a genuine reaction out of them.
* ExecutiveMeddling: Averted. When the rights to the film were initially purchased, the studio put the film on the shelf and intended to remake it with a larger budget and more famous actors in the roles; when audiences walked out of test screenings for the film ''because they were scared'', the studio quickly reversed their stance.
* FanNickname:
** Fans now call the demon Toby thanks to Kristi calling him as such in ''[=PA3=]''. In the later films, the name became canon, and apparently [[IHaveManyNames one of several names the demon has used]].
** ''Paranormal Activity: The Marked Ones'', due to its mostly Hispanic cast, has been called ''Paranormal Activity: The Marked [[JustForPun Juans]]''.
* FranchiseKiller: ''The Ghost Dimension'' may have been intended as a GrandFinale, but even if it hadn't, its poor performance at the box office, [[ExecutiveMeddling stemming partly from a VOD distribution strategy]] that caused some theater chains to boycott the film, likely would've killed the series regardless.
* ViralMarketing: Used heavily to market both movies. The second movie features a number of [[http://www.youtube.com/watch?v=EWscOORcgmw&feature=related viral clips]] on Youtube.
** Now there are recent channels on Facebook, Twitter, and [[http://www.youtube.com/user/jacobdegloshi Youtube]] that follows a man named Jacob Degloshi. The videos appear to be leading to Paranormal Activity 5 while giving more detail on the Featherston sisters' past.
* WhatCouldHaveBeen: The first choice to direct the sequel? None other than Brian De Palma, director of ''Film/{{Carrie|1976}}'', ''Film/DressedToKill'', and ''Film/{{Scarface 1983}}''. He considered the offer but turned it down.
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