Factual error: Ashley Judd is convicted of murdering her husband for the insurance money and that would make it a first degree murder charge (first degree meaning she planned the murder). Because of that there is no way she would have been eligible for parole after just 6 or 7 years.
Other mistake: On two occasions in the movie, Ashley Judd slams a car into another (she drives Tommy Lee Jones' car into another and over the side of the ferry boat, and later she smashes a stolen pickup truck into the side of a car). In each case, the car she is driving emerges from the crash without a scratch on it, not even a damaged headlight.
Revealing mistake: When Ashley Judd slams Tommy Lee Jones' car and tips it over, she drives off and skids dramatically to a stop. Just before she skids, you can see several skid marks on the ground from practice or previous takes.
Continuity mistake: When Libby goes to the BMW dealer, the dealer says the address is 20 Oriole Terrace. When Libby is driving down Oriole Terrace, she passes a house with four digits in the address.
Continuity mistake: In the scene where Ashley Judd leaves prison and first meets Tommy Lee Jones, she brings a box into his office full of her belongings. After he has checked through it he looks at the picture of Judd's son. When he throws it back into the box, it makes a noise as if it has hit the bottom of an empty box. In the next shot Judd picks up the box which now seems to be full with all of her belongings again, even though he hadn't put anything else back into the box.
Continuity mistake: In the opening scene where Libby is talking to Maddy. When the camera is in front of them, they're facing each other. But when the camera shows them from behind, they are sitting beside each other.
Factual error: When Libby tries to call the friend's house back after the 'resurrected' husband yanks the phone out of the wall, the tone she gets is fast beeping. That sound is the tone used when your phone hasn't been hung up properly. She should hear a ringing tone on her end since the phone she's calling is still in service.
Continuity mistake: When Libby asks Angie to adopt Maddy, in one minute her legs are up on the chair, and in the next, they're hanging down again.
Factual error: When Libby makes a phone call from jail, she states to the business that she is Angela Green and she wants to make sure that her severance check is mailed to the correct address. In real life, the business Libby called would've have never accepted the call under the assumed name of Angela Green because when you call ANYWHERE from jail there is an operator on the phone to tell the receiver of the call where you are calling from and who you are, and will they accept the call.
Factual error: When Libby uses the pay phone in prison, she puts a quarter in. Prisons don't require change to use the phone.
Factual error: When the lawyer shows the bloody knife to the jury, notice it's bright red. As time passes, blood dries and gets darker. The blood looks fresh, as if the murder just happened.
Character mistake: The Fifth Amendment Double Jeopardy Clause does not apply. Libby could be convicted of 1st Degree murder when she gets out and pursues Nick. It doesn't really matter to the plot, however, because it was what Libby believed to be true and motivated her. Further, she ends up shooting Nick in self-defense. So it's all good.