Continuity mistake: When Halle starts screaming while busting through the barricades, her windshield cracks on the lower driver's side. After the car stops there's no crack anymore. (01:04:40)
Continuity mistake: At the beginning of the movie when Halle Barry is talking with her husband in his office, every time a shot cuts to him sitting at his desk, the way items are arranged on the desk changes.
Continuity mistake: When Miranda (Berry) took the guard's car and skidded to a stop by the sinkhole the front passenger wheel was angled toward the driver. A few shots later as the camera pans away from the car the wheel is straight. (01:05:00)
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.
Answer: The blood is not from Miranda; the drop of blood is a sign from the "dead girl" to tell Miranda that she should go to the place in the pic. Miranda goes the next day and that's how she finds her husband was a sadist.