(at around 19 mins) Allison asks Marco if he can come to her office, when he get's there she says ,'you know my daughter Taylor '....when he's leaving the office he says ' nice to meet you 'indicating he'd met her for the first time.
Police detectives cannot transfer from one city to another, especially in another state, and be hired as a detective. They would begin as a patrol officer and then have to compete for the detective position as would any other officer.
(at around 1h 14 mins) When Heather is taking the detectives to the computer room she says is the second door on the left however she takes them to a door on the right.
Lucas shoots the mother, a police officer, with her own weapon, and the slide on the weapon locks open indicating there are no more bullets in the magazine. He only fired once, so that would indicate there was only one bullet in the gun to begin with. Moments later after her daughter hits Lucas and causes the gun to fall from his hands the mother presumably shoots him with the same weapon except the slide is closed.
Washington State has no highway patrol, it has a state patrol, so the police cars shown are prop vehicles commonly used in Canadian movies that are supposedly set in adjoining Washington State.
A continuity error takes place when Taylor is chasing Barb after Barb is outed. Taylor stops in front of a parked black car to answer her phone. When the camera angle changes, she is several feet into the street beyond where she had been standing. This is a plot hole as well since the person driving the car could not have tried to run her over if she was not in the street.
Police body armor does not cover the shoulder area where Allison was shot as evidenced by the blood shown on her shoulder as she was on her back after being shot. The shot would have impaired her right (gun) arm so she would not have been able to use her gun as shown.
During the webcam scene while Taylor, Zach, Hanna and Cody are talking about the release of Brandon the names guys names are backwards. Cody is labeled as Zach and Zach is labeled as Cody.
Hannah's mom is clearly sexually promiscuous yet she is shown as being shocked to the point of dropping her wine glass when she watches herself on video. Hannah's mom didn't know she was being recorded that's why she was shocked. Hannah and Zach knew "Truth and Lies" had recorded people via webcams, yet they start to have sex with the laptop open.