Continuity mistake: As Ben and Jane drive down the road, it is raining. After they hit the ghost, the scene fades to black. When the scene fades back in, it's heavily snowing, and a previously nonexistent thick sheet of snow is covering the ground. As they get out of the car, they start talking. During their conversation, there is a quick cut, and with this, it instantly stops snowing.
Continuity mistake: Jane brings her photos to the magazine guy who "knows" ghost photos. While she is waiting to talk to him, you see a gentleman working on a photo; he is adding a ghost face to it. The first time you see the screen, he moves the face into the top right corner. The shot cuts to Jane and then back to the gentleman, and now the face is in the middle of the photo and he is again moving it to the top right corner.
Visible crew/equipment: When Ben and Jane go to Megumi's house, Jane walks by a mirror and picks up a picture of Ben and Megumi. On the right side of the mirror you can see the reflection of someone's hand.
Other mistake: In the beginning of the movie, they're driving a red car and they crash. Then the police come and they drive away in a black car. There was no scene with a visible towing truck or anything. Did they forget to include them switching the cars or did they make an error of switching the car from red to black?