The cuts on Miranda's arm that spell "NOT ALONE" change starting positions throughout the movie. "NOT" starts at the elbow, then the wrist, then back to the elbow.
The length of Miranda's hair changes too much for the three week time span of the main plot in the film.
When Miranda flees from solitary after seeing Chloe and crashing into the two guards, she falls backwards with her head towards the solitary. In the next shot, she is lying the other way around, fighting.
When Sheriff Ryan comes to interview Miranda Grey the location of the bandage on her arm moves from the back of her arm to the forearm and back again.
When Pete talks to Miranda for the first time after the murder, and is crouched with his back to the cell door, two plastic cups are on the floor. As he rises, the cups have changed positions. One is lying on the floor, facing Pete.
When Dr Pete Graham is taking Miranda's blood pressure, as he squeezes the bulb to inflate the cuff you can hear the air escaping because the valve on the bulb is not closed.
When Miranda is telling Doug about the medications that have been used on Chloe, she mispronounces the last drug, Haldol, as "Hadodol." There is no drug called "Hadodol," and the film's closed captioning gives the correct word "Haldol."
When Pete is taking Mirandas blood pressure he holds the bell of the stethoscope against her arm with his thumb. This is incorrect for the same reason you don't use your thumb to check someone's pulse. The thumb actually contains a heartbeat too. If you use it to try to listen, as with the stethoscope when taking a blood pressure, or check someones pulse your likely to pick up the sound/beat of your own pulse. If you use your thumb to check your own blood pressure or pulse you will get an incorrect reading, because you'll be hearing/feeling your own heartbeat twice.
A psychiatrist who had a mental breakdown would never be committed to the same hospital where they formerly worked, especially because it's a hospital for the criminally insane, where patients would no doubt have grudges against Miranda. While Pete tells Miranda that he pulled a few strings to get her committed to her own institution so that he could be in charge of her care and be surrounded by familiar faces, she would still not be allowed to wander the hospital grounds alongside her former patients for her own safety.
The 40mg Ativan dose given to Miranda when she first awakens in her isolation cell is too high. A starting dose for a woman of her stature would actually be a single milligram, and for sedation purposes a clinician would administer 2-4mg at most to sedate her, so as to cause her to involuntarily sleep in the process. The 40mg given to her could potentially cause a coma, especially when combined with the Haldol (haloperidol, an anti-psychotic and sedative) they had also given her. It would be several days before she woke up and was conscious again.
When Miranda enters the shed, she is startled by an owl. You can hear it fly around. Owls fly silently.
When Dr. Pete takes Melinda's blood pressure, the needle on the pressure gauge doesn't move when he inflates the cuff.
In the storm scenes, the rainfall patterns are circular, a sign of rainmaking machines.
When Miranda escaped from her cell the second time, the nurse who tried to close the grated fence door to keep her trapped on the cell floor clearly paused in her efforts to wait for Halle Berry to arrive and push the door back open.
There is a scene in which Dr. Pete is taking Melinda's blood pressure. He wraps the cuff around her arm and begins squeezing the bulb but the needle NEVER moves! You are supposed to pump air into the cuff until the needle reaches AT LEAST 200 on the scale, then slowly release the air and listen through the stethoscope.
At the end of the movie, they are supposed to be in New York City. However, as Chloe is getting into the cab, you can see a (partially burnt out) Tim Horton's sign in the background. Tim Horton's is a Canadian coffee shop not found in New York. However, in the years after this movie was made, Tim Horton's did open shops in New York.
There would never be just one person alone running a sheriff's office overnight, especially not if there was a prisoner being detained.
Miranda hides from the guards under the desk of another security guard, who lets her escape by giving her his car keys and giving wrong directions to the other guards. While the audience knows she's actually innocent, as far as everybody in the movie is aware, she's an escaping mental patient who previously committed a murder. Why did this security guard let her escape? They only shared one scene together and a few lines, so it doesn't even feel like they actually knew each other personally or were friends, therefore he wouldn't have believed her story.
Miranda and the other doctors regularly throw around the word "crazy" to refer to patients or Miranda herself, yet this is a stigmatized (and inaccurate) word medical professionals would not use so lightly.