Sam has brown eyes even though both of his parents have blue eyes. This is genetically impossible, as two blue-eyed people can only have blue-eyed children.
Eye color is not a factual mistake. Eye color is determined by variation at several different genes and the interactions between them, this makes it possible for two blue-eyed parents to have brown-eyed children.
The handheld radios in use are Pye PF1 Pocketfones, however that model had two units - the one with the external pop-up aerial is the transmitter and the receiver has a built in aerial which is the speaker grille. They are using just the transmitter and pretending it's both the transmitter and receiver. The Sweeney (2012) and The Professionals (1977) all did the same thing.
The handheld radios in use are Pye PF1 Pocketfones, however that model had two units, one with the external pop-up aerial is the transmitter and the receiver has a built in aerial which is the speaker grille. They are using just the transmitter and pretending it's both the receiver. The Sweeney and The Professionals all did the same thing.
In the very last shot of the episode as the characters drive away in the Ford Cortina, a CCTV camera can be seen on the right of screen.