Plot hole: In the shower scene when Miranda is being cut, everyone in there, including the guard, sees her getting the cuts out of nowhere. Yet they all say, she did it to herself with a scalpel although one was never seen or found. Don't they think if she did it to herself, they would've seen it?
Continuity mistake: In the scene where Miranda escapes and goes back to her house, we see flashbacks to her husband's murder, including one of Miranda in the bathtub filled with water stained red from blood. When the flashback ends and we return to the present, the tub is spotless, even though there should be at least remains of blood there.
Plot hole: There's no way the guards couldn't see Miranda in the swimming pool. For one, you can see clear to the bottom of the pool. And their flashlights shined clear to the bottom. And when she emerges, she screams. They should've heard her since they just exited the pool area.
Plot hole: You are the police looking for an escaped madwoman who killed her husband and is in denial. Where is the first place you would look? If you said her house, congrats, you are smarter than the cops in this movie. Yet Halle Barry manages to spend the entire night there (she escapes just after midnight) crying over pictures without so much as a knock on the door.