Music was composed by Ken Freeman, who also composed the theme tunes to Casualty (1986) and Holby City (1999). His score for the unmade third season is on the DVD.
The third season was cancelled during the production of the second season by the new BBC One controller Michael Grade, who disliked science fiction and considered the programme an expensive ratings failure.
Charlotte Long, who played "Eloise de Ricordeau", tragically died in a road accident at the age of just 18 before her episodes of the series aired. After her death, Long, who was roughly the same age as her late teenage character, was replaced in a hallucination sequence by Cindy Shelley who was in her mid twenties at the time. Shelley had no dialogue but her image replaced Long's in footage of a photo carried by the series protagonist, Will Parker. Some thought this unnecessary as the original image was used in a recap of season one a few weeks previously.
The village scenes were shot at Portmeirion, Gwynedd, Wales.
The series was based upon the Tripods trilogy of children's books: "The White Mountains" (1967), "The City of Gold and Lead" (1967) and "The Pool of Fire" (1968) by John Christopher. Only two of the intended three seasons were produced - the events of the third novel are therefore missing in this adaptation.