Filmed on location in Co Kildare in Ireland. Brennan's Kilteel Inn was rebranded as The Hairy Goose for the duration of filming.
All of the the books depicted in the opening credits are real except for 2 which are crucial to season one episodes 1 and 8; 'Calabras' and 'Bleed She Said'.
Every episode of season two has a dedication in the end credits to the memory of James Flynn, who was an executive producer of Harry Wild. He died in February 2023.
Morgan C. Jones has appeared in three episodes as Professor Graham Gray. Season one episodes 1 & 2 also season two episode 1.
Samantha Mumba (Paula Kenny, Fergus's mother) is only 11 years older than Rohan Nedd (who plays Fergus).