Mr. Saunders calls Mrs. Brown his little sweetbread. While it was standard to express affection with terms like 'honey bun', 'sweet cheeks', or 'sugar pie' Mr. Saunders was a butcher. To him 'sweatbread' meant the pancreas, thymus, and sometimes salivary glands of a calf or lamb. Only a butcher could deem offal organs endearing.
Martin's recitation, "Come live with me and be my love; and we will all the pleasures prove." is from Christopher Marlowe's 'The Pasionate Shepherd to His Love'. Marlowe was the second best playwright during the days of Shakespeare.
Martin calls Brennan "Hawkshaw". In 1863 the western world's first detective play "The Ticket-Of-Leave Man" introduced Detective Hawkshaw. For several decades in the 1900s, Detective Hawkshaw was a newspaper comic strip.