When Sarah Michelle Gellar is on the bus with her boyfriend, she sees Kayako face looking at her in the window reflection and panics. When she looks back at the window she sees the normal reflection of her face. Trouble is, her reflection is turning her head and looking side to side, whilst Gellar herself is looking straight and not moving her head at all.
The Saeki family, the ghost family that haunts and terrorizes everyone who enter their home, are no strangers to the Grudge franchise. They played the same characters in the movie Ju-On, the Japanese version of The Grudge.