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 book of recorded temperatures shows continuous entries from March 5 to May 2 1973. During this time the recorded temperature goes from 9°c to 14.9°c.
In a 2023 interview with Senses of Cinema, Mark Jenkin told a story of a remarkable coincidence that took place during the shooting of the film: "The interesting thing about the hands is that I really cast the hands. So, when we did Bait (2019), all the close-ups of the hands of the protagonist - they're not his hands. I used another actor's hands that I preferred. It was Joe Gray, who's the production designer, who plays the miner at the cottage in Enys Men, it was his hands we used for Edward Rowe's hands in Bait. In Enys Men, it's not Mary Woodvine's hands, it's my first AD, Callum Mitchell, his hands. He's got very beautiful hands and they look a lot like Mary's hands, and this is incredible - talk about the angels of happenstance shining down - Mary's got a finger on her left hand, she's got a tendon that tightens and it sort of closed her finger up. So, in Bait, she's got a finger like that [gestures a bent finger] and after Bait she had it operated on, to have it straightened, but it straightened to about there [gestures a slightly bent finger]. Her left hand is very distinct.
Callum, I cast him to do all of the hand stuff for Mary, so all of the writing is him in close-up. About a month before the shoot, he rang me and said, 'Oh, just to let you know, I was at football training earlier and I went to catch the football and I've totally smashed my little finger, and I'm going to have an operation on it and it's completely deformed.' And I said, 'What hand is it?' and he said, 'On the left', and he sent me a photo of it, and it was bent like that [gestures as before] and his finger's permanently bent exactly the same as Mary's. And we went to the shoot and he's got the same little finger. How did that happen? That was going to be something that we were going to have to hide, Callum's left hand, because it looked different to Mary's left hand. But then we made a feature of it, and I put it in deliberately, but nobody will ever notice, because it looks like that's how she's holding her finger. But that's a permanent injury that both of them have got that's exactly the same... I think it's Andrew Kotting who said to me that Iain Sinclair always describes the angels of happenstance [as]: if you leave yourself open to chance and don't try and control everything when you're making a film, you'll be rewarded by coincidence and good luck, which I think, when it's the absolute carnage of making a film, I do sort of put faith in those things quite often."
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".