* TheDanza: Yoko Maki as Yoko.
* ExecutiveMeddling: Kayako did not have much of a backstory in the original film series, and Takashi Shimizu wanted to keep it that way. However, he was told to give her a backstory for ''The Grudge 2'', which he reluctantly went ahead with . In an interview, Shimizu also stated that executives kept insisting that Kayako should have "a twin", which baffled him. In ''The Grudge 3'', Kayako is revealed to have a sister (though not a twin sister), which has to make one wonder if that was a case of executive meddling, too.
** As with the original ''Ju-on'' series, Toshio has been portrayed by three different actors. In the first film and in flashbacks/photographs for the second and third films, he was portrayed by Yuya Ozeki (who also portrayed the version of the character in the two theatrical ''Ju-on'' films). In the second film, he was portrayed by Ohga Tanaka. In the third film, he is portrayed by Shimba Tsuchiya. (Unfortunately, the difference is rather jarring in the third movie, as Toshio looks a lot older than in the previous films.)
** Not only that, but Creator/TakakoFuji, who has played Kayako from the very beginning of the ''Ju-on'' saga up until ''The Grudge 2'', has been replaced in ''The Grudge 3'' by Aiko Horichi (although Fuji does appear as Kayako in the third movie's flashbacks and photographs). According to [[WordOfGod Takako Fuji herself]], she was getting tired of playing the same role over and over again. Also, in the ''Tales of the Grudge'' shorts, Kayako is portrayed by Anna Moon.
** Selma Blair was the first choice for the role of Karen.
** The role of Vanessa in ''The Grudge 2'' was originally written for Vanessa Lengies.