John Corbett's Range Rover registration plate contains a Q, however the letter Q is not used in UK plates, except as a prefix where the vehicle's main identity or age may be in doubt, for example, custom builds from components of different vehicles from different years, where a Q-plate is issued upon request.
In the scene where Kate and Steve attend the forensic examination of the jetty, in the final shot, the river is completely static possibly because a photo of the river was used for the green screen background.
The video footage captured by the boy on the bike is paused at 5 seconds into the clip, it's restarted and handed to John showing 15 second into the clip. The video continues playing but the image is now static, it's clearly a still of Steve stood in front of the phone box, not a video.