- California Doubling: The scenes in Northmoor were filmed in Wales.
- Creative Differences: Martin Campbell clashed with Troy Kennedy Martin, demanding rewrites, in particular to the notion that Craven had known about Emma's involvement with GAIA right from the start; this was removed at Campbell's behest. Further clashes over the script occurred between Kennedy Martin and Bob Peck over the conclusion in which his character would turn into a tree; Peck recalled that it didn't seem to be working in script terms, it seemed as though we wouldn't be able to make it work for the audience, a view echoed by Michael Wearing who felt that it was likely not to come off as an effect. Kennedy Martin capitulated, introducing instead the concept of the black flowers seen in the finished production.
- Doing It for the Art: Joe Don Baker was so impressed by the script that he agreed to work for less than his usual fee.
- Executive Meddling: Downplayed example. The American co-producers asked that Joe Don Bakers character be introduced in the first episode, a request Troy Kennedy Martin found easy enough to satisfy
- What Could Have Been:
- The original script was about trade union problems in the nuclear industry.
- The original ending had Craven turn into a tree.
- Working Title: Magnox, a reference to the Magnox type of nuclear reactor.
Trivia / Edge of Darkness