The author of the book that is the root of the strife between the two villages is Ellis Bell. Ellis Bell was the pseudonym of Emily Brontë.
The bookshop is actually Penn Cottage Bookshop, in Penn, Bucks, which was famously a popular destination in early life for Terry Pratchett (author of Discworld series).
The character Simon Smythe-Webster refers to "the weasels in the wild wood", which DCI Barnaby correctly identifies as a line from Kenneth Grahame's 1908 children's novel, "The Wind in the Willows".
Troy tells Barnaby that the first victim is an actor who starred in a (fictitious) series called Diamond Geezers, 2 years later there was a real series called Diamond Geezers.
The character Laura Smythe-Webster quips, "And then there were four" after the second death. This is a reference to the nursery rhyme "Ten Little Soldiers", found in what is widely regarded as Agatha Christie's 1939 masterpiece "And Then There Were None".