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)
Continuity mistake: When Yoko opens the door and ventures into the attic, the slide-door she pushes is nearly fully open. Yet when we see the shot of Yoko's legs dangling, the door is now much further shut. (00:06:20 - 00:07:35)
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.