Deliberate mistake: When Sook-Hee is first shown her bed chamber, just after Sasaki leaves, she slides open the door to Hideko's room to look inside. After a 5-6 second silence, a thump sound is heard and Sook-Hee quickly closes the door. Later in the movie, when this same scene is shown a second time from Hideko's perspective, the thump sound, which is revealed to be Hideko banging her doll against the wall, occurs 11-12 seconds after Sook-Hee slides the door open. (00:06:38 - 01:32:33)