In the playground seen early in the film, Karen is by a bulletin board with an ad posted with a 604 (British Columbia, Canada) area code. In the 15th minute Karen arrives home driving a car with a contemporary California licence plate. For the record, this is a USA/Canada co-production.
In the 96th minute after she had shot Megan and is at home with her husband, fluid (mucous or tears) is visible between her nose and mouth; this fluid is gone in the next shot.
In the 100th minute when Dave finds Megan's body, it is not where she was shot and collapsed earlier.
In the 17th minute when Karen visits her friend, in between shots her face goes from introspective or sad to smiling as Megan says, "...we'll get your room ready."
In the final scenes, the ambulance has no unit/vehicle ID number.
In the 114th minute as Haley/Emma is in the bathroom with the door locked, Susan manages to toggle the bathroom door handle. It could not be toggled to this extent if the door is locked. A locked door handle has limited toggle range.
In the 80th minute, a can of pop left by Karen on Megan's kitchen table reads 'Cola (...) Trade Mark.' This makes no sense as a generic cola or other beverage cannot be trademarked. Also, the format 'Trade mark.' is incorrect.
It seems unlikely that twelve years after their child was abducted, a parent would be calling a police detective.
In the 29th minute when Karen is photographing a schoolgirl with braces, she instructs the girl to smile, but she is already doing so. This could be Karen just going through her routine, but it seems unlikely that a movie would allow this in the dialogue (i.e., there is seldom coughing or erroneous dialogue, pauses or stutters unless relevant to the plot.
In the 71st minute when entering the unlocked back door of a house, it's unrealistic that Karen would use two hands on the doorknob, as if she's breaking in.
In the 12th minute when Karen ODs, the first person to enter her bedroom is the detective. It's unclear and unlikely he would be at her home and that he would be the one to find her, rather than her sister. Also, one hears sirens seconds later, yet no one has called 911, so EMS would not have been notified.