During the credits, certain letters of people's names are red instead of white - I will indicate via parentheses where the red letter is: "Location Managers . . . Ben Mangha(m)" "Production Accountant . . . Dav(i)d Jones" "Production Manager . . . Claire Hi(l)dred" "Unit Managers . . . Da(v)id Gunkle" "Assistant Grip . . . Ow(e)n Charnley" "Production Buyer . . . Blaanid Madd(r)ell" "Construction Manager . . . Mark Pain(t)er" "Dubbing Mixer . . . H(o)ward Bargroff" "Executive Producer for MASTERPIECE . . . Rebecca Eato(n)" The red letters spell out MILVERTON, a reference to the Sherlock Holmes Adventure "The Adventure of Charles Augustus Milverton," which is a significant source of inspiration for this episode.
At the very end is Jim Moriarty saying "Miss me?" but in a regular video and not the animation style that appears in the episode.