"Torchwood" is an anagram of "Doctor Who". When the first series of "Doctor Who" (2005) was being made, television pirates were desperate to acquire the preview tapes. One of the people in the office had the idea of labeling the tapes with the anagram "Torchwood" rather than "Doctor Who", as a security measure to disguise the tapes when they were delivered from Cardiff to London. Writer Russell T. Davies liked this idea so much that it later inspired him to use it as a title when creating this spin-off series.
"Torchwood" is the first Doctor Who spin-off to make it to series, and the first dramatic spin-off of "Doctor Who" (2005). A failed attempt to spin-off a series from the original "Doctor Who" (1963) resulted in the television special, K-9 and Company: A Girl's Best Friend (1981) (TV), featuring the characters K9 and Sarah Jane Smith. After failing to produce a series, the pilot was broadcast as a seasonal special.
In certain episodes, Torchwood members use a drug called "Retcon" to wipe the memories of people who know too much about the organization. Retcon is a term derived from "Retroactive Continuity" and is used in serialized fiction, especially comic books, for when new events effectively change or erase the established history of a series.
Torchwood was the subject of a background arc during the 2006 series of "Doctor Who" (2005), with most episodes containing at least one reference to the Torchwood Institute, beginning with the 2005 series episode "Bad Wolf" and culminating in the Institute's appearance in "Army of Ghosts" and "Doomsday". The 2006 episode "Tooth and Claw" details the origins of Torchwood. After "Torchwood"'s debut, it was referenced again in the Doctor Who Christmas special, "The Runaway Bride".
Although "Torchwood" is officially a spin-off of "Doctor Who" (2005), Russell T. Davies had the idea for the series before working on "Doctor Who".
Owen is the only member of the Torchwood team never to have had direct contact with the Doctor. Jack has been companion to both incarnations, Toshiko met the ninth Doctor while examining the space pig in "Doctor Who: Aliens of London (#1.4)" (2005), while Gwen and Ianto met the tenth Doctor through the sub-wave network in "Doctor Who: The Stolen Earth (#4.12)" (2008).
In several episodes throughout Season 1, posters bearing the slogan "Vote Saxon" are visible in several shots, most noticeable in episode 12 ("Torchwood: Captain Jack Harkness (#1.12)" (2007)) on the door of the dance hall.