Other mistake: In the final scene, where Ben realises he's inside the mirror world, everything is mirrored. However, the word ECNALUBMA is visible on the ambulance. Since the word ambulance is always written mirrored on ambulances, it should have shown AMBULANCE.
Other mistake: Even though the building is said to not have power and the guards have to use flashlights, the first time Keiffer goes in the basement he is able to flick the switch and turn on the lights.
Visible crew/equipment: After Ben imagines himself on fire, there is a shot of him from behind just before he finds the wallet of Gary Lewis. In the upper right corner a boom microphone is visible that slowly moves out of the frame. (00:27:20)
Continuity mistake: Just after fake Amy in the mirror starts to cut her daughters neck slightly with the scissors, the real Amy having escaped the bathtub grabs her daughter and puts her in the corner of the room. Soaking, she removes her top exposing her right breast and nipple - next shot she has a soaked singlet on which wasn't there a second ago.
Other mistake: When Ben takes a pill, he leans over the sink and his left hand has a bandage on it. In the following scene, he cuts his hand and bandages it. (00:22:55)
Continuity mistake: When Amy Smart gets into the bathtub after looking at herself in the mirror, there's very little foam on the water. Then there's a cut back to the mirror and in the following shot there's suddenly a lot more foam. (00:45:30)
Revealing mistake: At the beginning of Angela's bathroom death scene she is looking at herself in the mirror. You not only see her reflection in the mirror, but also in the shiny metal strip holding the mirror at the bottom which is to be expected. When she turns away and her 'demon' reflection is watching her, you still see the image in the metal strip. As the 'demon' is in the mirror you should no longer see anything reflected in the metal. This does seem to show how these moments were filmed, with the real actors reflections being recorded.
Other mistake: After imagining himself on fire, Ben rubs his hands all over his white shirt. Despite the fact that his hand was recently cut, there is no blood transferred to his shirt.
Other mistake: In the scene where the mirror cuts his hand, Ben touches the mirror with his left hand. In the very next shot he is holding the flashlight with his left, pointing on his wounded right hand. Right after that he switches hands again. (00:23:35)
Revealing mistake: In the scene at the morgue, after Amy Smart's death, Keith Sutherland is holding her hand before putting it under the sheet. Her hand should be cold, but when it's moved a hand print is left on the steel slab due to condensation from her warm and very much alive hand. (01:36:45 - 01:37:55)
Other mistake: In the scene where the son is woken up by the "screaming woman", when the mother rushes out of her room you can see the sun in the window behind her, despite the the fact the scene takes place at night.
