During the opening credit sequence, one of the cell phone ring-tones is the theme song from an earlier Takashi Miike film, Gozu (2003).
In the Philippines, the movie poster carries the tagline "For the creators of The Ring and Juon: The Grudge 2." The two mentioned movies have no connection with this movie (except both movies also came from Japan where this movie was originated).
A few scenes in the film are meant to be an homage to other J-horror classics, including: * Yumi racing against time to discover the secret of the curse before she's scheduled to die is lifted from Ringu (1998), the film that mostly inspired this one. * The ghostly child hiding in an apartment cupboard is inspired by Ju-on: The Grudge (2002). * The scene featuring an old residential building with a water tank on the roof, which then cuts to a shot of characters ascending in an elevator, is an homage to Dark Water (2002). * The premise of ghosts terrorizing the lives of humans via technology is reminiscent of Pulse (2001).
In the child's room there's a drawing of Card Captor Sakura and Kero.