When Anna gets a cold, Mrs. Hughes orders her to go to bed and says she'll bring her up a Beecham's Powder. While Beecham was an old and established pharmaceutical brand at the time, the product Beecham's Powder was not introduced until 1926.
Part way through the episode a maid (Anna) is sent to bed sick, and the cook says she will send up a Beechams Powder. Whist the Beechams company did exist in this period, Beechams Powder wasn't sold until 1926, several years after this episode is set.
The reason for Gwen and Sybil's delay in returning from a job interview is that the horse pulling the trap had thrown a shoe, forcing the girls to walk. The horse appears fully shod with shoes visible on all four hooves as it is being walked to a blacksmith.