When Stephen Pierce's typed statement is shown and Davies reads it out load, both visibly and audibly it says that Pierce came on duty on the night in question at 8pm. When Pierce is interviewed by Davies in the car, Pierce confirms Davies's suggestion that he came on duty at 10pm. Although the typed statement does contain some untruths and omissions, the time that Pierce came on duty is not among them and Davies isn't trying to trick him by suggesting a wrong time.
When the couple drop the victim off at the cemetery (in flashback), the view from the car shows her on the right side of the window (most likely front), squatting by the entrance pillar. When the last person to see her alive describes his flashback, she is shown exiting the left side of the vehicle, and going behind the car to squat at the pillar. There is no way she could appear to be on the right hand side of the vehicle front inside the car based on the second flashback.