Offred says that the Handmaids always have to go everywhere in twos, but Ofglen walks to and from the Commanders house alone.
When the matron signals the Handmaids to start and end the attack on the prisoner she blows a whistle. It is obviously an Acme whistle like as used by the London police. That whistle has no internal 'pea' like an American coach's whistle, and the sound of the Acme whistle is a solid tone. Yet the sound we hear is that of a whistle *with* a pea.