When Sophie writes a message on Josh's trailer, it is clear that her marker is running out of ink as the letters gradually become lighter but in a late scene the letters are written in bold with no signs of fading.
When Bobby's car is found outside 'Heaven', the registration (as observed by Tom and Pete) is BOBBY1. There is no way that this could be configured with any past or present UK registration number scheme (even if 8s were used as Bs - which it can be seen that they clearly were not).
When Tom goes to the community centre, his wife's former assistant has no idea that Jenny is missing. At this point, the 16-year-old girl has been gone for two days with no communication and no sighting of her. The police would have issued a massive alert and her disappearance would have received significant local media coverage. As there is no ransom demand or reason to keep her disappearance a secret, it is inconceivable and not explained why the police have not issued pleas to the public concerning her welfare.