Revealing mistake: When Karen is searching the net, she is on "www.tdn_japan.con" [sic]. This address wouldn't work... Also the Google bar spells "Imaegs" not "Images." (00:59:30)
Revealing mistake: When the detectives were listening to the message on the answering machine, we heard it say the date was Thursday and states a time the message was left. When the camera shows the answering machine, you can see the display blinking between 1 (the current message) and CL (which indicates the time and date have not yet been set).
Revealing mistake: In the scene Where Karen is taking a shower and fingers show up on her head, she jumps and on the bottom left you can see she is wearing something red, and is not naked.
Answer: Well, in the Japanese original (Ju-On: The Grudge), it shows that Takeo, the father, killed his wife by shoving a knife down her throat or something similar to that. When he was killing her, she tried to scream, except her scream came out all messed up (because the knife hit the vocal chords), which explains the horrible croaking noise. There's no doubt about it that it's the way she was killed in this version.