A hand double was used to write in the log book throughout the film. Mary Woodvine claimed her writing was deemed 'not up to scratch' at a Q&A in London.
Mark Jenkin had said that this film took him "three nights" to write and that it was written by hand in a notebook
The Preacher is played by Mary Woodvine's father John Woodvine, a well-established actor with nearly 200 screen roles. He appears in this film at the age of 92.
Although set at the opposite end of the British Isles this film has several elements in common with The Wicker Man (1973), including a small island populated (in this case, formerly populated) by an isolated Celtic community, and in both films a group of white-clad children are seen dancing ritualistically. This film is set in 1973, the same year that Wicker Man was released.
On the plaque at the pier that commemorates the people lost on the Senara lifeboat, at the bottom it says Onan dhe'n oll. In Cornish this means "One for the All" or "One for All".