(at around 5 mins) It is raining when Ben and Jane drive down the road. When they hit the ghost, the scene fades to black. When the scene fades back in, it's snowing heavily, and a thick sheet of snow covers the ground. They start talking as they get out of the car, and the snow stops.
The morning after the road accident, Benjamin and Jane are taking pictures of themselves outside. Benjamin is on our RIGHT hand side with Jane on our LEFT. A few minutes later, the pictures are shown to us. Benjamin is now shown on our LEFT with Jane on our RIGHT.
When Jane looks at the photographs that Ben has done she puts her bag down, but when she turns around to tell Ben what she sees in the picture, she puts her bag down again.
(around 26 minutes) When Ben removes the towel from his face right before looking at the mirror you can see that his face is clean.
(at around 17 mins) At one point, Jane says she must call New York, but Ben says it's 3am there, yesterday. This is a mistake. If it was 3am in New York, in Tokyo it would be 4pm in the afternoon on the same day (give or take an hour for differences in daylight savings).
(at around 14 mins) While in the honeymoon cabin, the camera Ben is using is clearly a medium format camera. Later however, when they are looking at the pictures Seiko dropped off, the negatives attached to the envelope are 35mm negatives.
When Ben and Jane find Megumi's body, she's in a closed-off room which is filled with toxic cyanide gas, but neither of them appears to be physically affected at all.
(at around 51 mins) When Adam is taking the pictures of the brunette in the cowboy hat a flash effect is used but the camera does not have a flash attached.
(at around 27 mins) In the closeup shots, red circles are shown highlighting anomalies in the photos. In the panorama shots, the red circles are missing.
(at around 3 mins) When Ben and his wife take a picture of themselves in the beginning, the camera is obviously not on.