The poem found by Charlotte and read in voice-over is part of Emily's 'The Prisoner'.
In shots from the very top of the parsonage staircase it is possible to see on the left-hand wall Branwell's second group portrait of his sisters, called "The Gun Portrait," painted in about 1834 and now lost. The portrait was mostly destroyed by Charlotte's widower, Arthur Bell Nicholls. Only a fragment remains, called "The Profile Portrait," which now resides in the collection of the National Portrait Gallery in London.
A shot of Branwell lying unconscious on his bed surrounded by papers is based on the 1856 painting 'The Death of Chatterton" by Henry Wallis, now in the Tate Gallery, London.
In an Express newspaper interview on December 29 2016, director Sally Wainwright revealed that constrictions in running-time had meant cutting almost all of both scenes featuring her 'Happy Valley' actor James Norton. In fantasy sequences he was the dashing Duke of Zamora and had a duel with 'Napoleon' as the Duke of Wellington. He can be glimpsed as the latter in an early scene.
The opening voice-over is Charlotte's poem 'Retrospection'.