* CompletelyDifferentTitle:
** China and Taiwan: ''Strange Kill''
** Czech Republic: ''Them''
** Greece: ''Did You Lock It?''
** Hungary: ''They're Uninvited''
** Turkey: ''Visitors''
* DawsonCasting: Minor example. Various lines of dialogue suggest the protagonists were in their mid-twenties (possibly just out of college); Scott Speedman and Liv Taylor were both in their thirties during production.
* DuelingWorks: Probably not intended by the producers, but a lot of film critique/discussion forums compare/contrast this movie against the previous year's ''{{Film/Vacancy}}'' for their similar premises and possibly the fact that their respective stars, Creator/ScottSpeedman and Creator/KateBeckinsale, are the leading cast members of the first two ''{{Film/Underworld|2003}}'' films.
* TheForeignSubtitle: Became ''The Strangers: Horrifying Visitor'' in Japan.
* SequelGap: There's a 10-year gap between the first film and the sequel.
* WhatCouldHaveBeen: There were originally plans to have the final scene between the couple and the killers be more dialogue-heavy. It was cut down to an exchange of two lines for the sake of keeping everything about the killers mysterious.
** In keeping with the killers being based off the Manson family, the original draft showed them being music fans (with Bagman asking Kristin how she knew a song [[spoiler: ''after stabbing her'')]]. [[NarmCharm It’s not hard to imagine why this aspect of the characters were removed.]]