At the end of the movie when Zachary pulls Adam into the closet you can clearly hear the doors close yet later the door is cracked open.
When Paul steps out of his car on the bridge, Adam's bicycle moves from the middle of the bridge to the side of the bridge, but we don't see anybody move the bicycle.
As Jessie walks to the photo gallery, her coat changes from a non-hooded coat to a hooded coat when she stops to look in the window. As she walks inside, she again has the non-hooded coat. When she walks out and down the street to take the call from Richard, she has the hooded coat again with sunglasses.
At the beginning of the movie, when Paul is mugged by his former student, he drops the present he is carrying and the wrapping becomes loose. When he picks it up, the wrapping is still intact.
A couple at a clinic and there's snow on the ground, they're taken to a house and there's no snow. Later the wife leave school and there's no snow but there is when she arrives at the clinic.
After a scuffle at a funeral service a lit candle is knocked over and within seconds the fire has spread over the altar, which is far too quick.
Right after the son is killed, there is a close up shot of the family answering machine. This model of Panasonic answering machine does not have a protruding round red LED to signal new messages. It has a rectangular LED that is flush to the body of the machine.
The ambulance has no unit ID number.
Adam is knocked out by Wells and when his wife searches for him she looks in a shed and he's suddenly there.
When Paul Duncan is driving, a Canadian flag is just about visible in the background.
Misspelling of the word "Disappearance" in one of the newspaper headlines at the end of the movie