(at around 26 mins) When Trish enters Jake's room, the floor in front of him is empty, and the camera turns to face Trish. When it's put back on Jake there is some kind of sport equipment on the floor.
(at around 1h 8 mins) When Audrey enters Eason's dark room, she turns on the lights, but seconds later the light is red again.
Vanessa passes by a woman carrying shopping bags when she's running down the street. In the next shot however, when she reaches the phone booth and opens it, the woman is gone from the sidewalk.
Vanessa didn't close the phone booth door when she entered it. In the next shot however, as she's trying to call Miyuki, the door is suddenly closed without her having touched it.
The Dutch Blu-ray of the film incorrectly lists Sam Raimi as director on the cover when he only produced the film. Takashi Shimizu is the director.
(at around 1h 8 mins) When Aubrey goes into the dark room and picks up the picture, the picture should be black. It was in the developer last. It would have had to go into the stop bath to stop developing, and then the fixer to not go black when it was exposed to real light.
The runtime listed on the back of the Dutch Blu-ray has a typo. The listed runtime is 98 minutes but upon watching the disc, it can be seen that the runtime is actually 108 minutes (the unrated cut).
(at around 1 min) Trish, under the influence of The Grudge, hits Bill, her husband in the head several times with a frying pan. In close scenes, the frying pan is a heavier cast iron model. However, when the pan is showing in closeups it's a much lighter non-stick model. While this would be very painful, the pan being as light as a nonstick unit, would have not been fatal as the film portrays it as being.
(at around 57 mins) When reading the diary, the characters read the book left to right, like a book written in English. Japanese, when written in tategaki format (top to bottom) or yokogaki (left to right), still is opened and paged right to left. However, the characters correctly read the printed book in the same scene.
When Aubrey arrives at the hospital and tells the nurses she's looking for her sister, Eason helps her by speaking to the nurses in Japanese, but he uses the term for younger sister (imouto) when introducing her. How does he know she's Karen's younger sister? There isn't a clear age difference - and Aubrey is taller than Karen.
(at around 14 mins) Right before Audrey walks into the house, there's a table lined with pictures and as the camera is passing by you can get a quick second-long glimpse of the camera as it passes.
When Vanessa was scared by Toshio, you can see boom mic is visible (Fullscreen only).
The curse is established to spread like a virus, affecting people even if they don't enter the house and simply meet someone who did for instance. So then Michael should not still be alive because his girlfriend Miyuki did enter the house and come in contact with the curse.
The School Counselor (Eve Gordon) entered the cursed Saeki home and died as a result, being claimed by Kayako. However, Allison is sent to her office in the middle of school hours after she has been killed, where she reveals herself to be dead and having been a ghost the whole time. This would imply that, even after having been killed, she still clocked in and entered the premises as an employee in ghost form. It is possible though that Kayako was puppeteering her spirit to torment Allison but it's unclear.
Trish is on the phone when Bill arrives, claiming he'd forgotten his keys (but then they are seen in his hand, being squeezed so tightly his hand begins to bleed), but when Trish says she'll go look for them she just hangs up the phone without addressing the caller again.