* TheDanza: Everyone in the first film.
** "Katie Featherston" is played by Katie Featherston
** "Micah Sloat" is played by Micah Sloat
** "Amber" is played by Amber Armstrong
** "Dr. Fredrichs" is played by Mark Fredrichs
* DuelingMovies: With ''TheFourthKind'' for the first movie and ''{{Saw}} VII'' for the second movie.
* EnforcedMethodActing: Much of the dialogue for the first film was unscripted, with Katie Featherston and Micah Sloat 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=].
** Paranormal Activity: The Marked Ones has been called Paranormal Activity: The Marked [[JustForPun Juans]].
* HeyItsThatGuy: Despite the series's stance on lesser known actors, [=PA4=] had some recognisable faces. [[Series/TrueJacksonVP Ryan]] is Alex's boyfriend Ben and Alex is in Film/BadTeacher.
* 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.