I've sort of assume they filmed the "hunter" scenes in the office afterwards tbh, and a few of the chase scenes are also shot again.
Not sure why a few seem genuinely outraged at such a thing happening though, watching an episode of folk staring at laptop screens of CCTV, or watching a chase which consists of a camera pointed at grass as the camera man sprints, would be dreadful.
I don't think there's rules in place about what the contestants must do, though, the singer boys were barely in it as they'd pretty much just camped out in Wales or something. While I think the ex police boy was just arrogant as f**k and assumed he'd be able to get away with meeting his family. They clearly get told that they have to enter the USB on a certain date aswell, which maybe dictates them getting closer to towns and that near the end.