To portray the aftermath of the shipwreck in the Isles of Scilly, dozens of extras had to lie in the cold surf, pretending to be dead, for over an hour.
Jeremy Irons' character, Rupert Gould, is only mentioned in one paragraph of Dava Sobel's book. When he was writing the screenplay, Director Charles Sturridge conceived the idea of telling Gould's story in parallel with Harrison's. This gave modern audiences a more sympathetic and relatable character to follow through the story.
Jonathan Betts, who was Curator of Horology at the Royal Observatory, served as a consultant to the production. He gave Writer and Director Charles Sturridge access to the notes and diaries of Rupert Gould, which helped flesh out the twentieth century portion of the story.
The shipboard scenes were shot aboard three different working ships, then edited to give the impression that it was all happening aboard a single vessel.
Jeremy Irons agreed to take the role of Rupert Gould in part because of his friendship with Charles Sturridge, who had directed him in Brideshead Revisited (1981). To prepare for the role he read Gould's diaries, and studied Harrison's clocks at the Royal Observatory.