Captain Jack Harkness - S1-E12
Factual error: When Gwen finds Toshiko's hidden message from 1941, she realizes that it was written in blood, and her flashlight reveals the bright red letters on the now-yellowed piece of paper. But after 60+ years, the iron in the blood would oxidize. The writing on the note should be rust-brown, not red. (00:33:40)
Chosen answer: As long as Jack's been in charge of it, Torchwood Cardiff has had a different agenda than Torchwood One. Tosh and Owen were there to watch for signs of the 10th Doctor, however, it was the 9th that showed up when the ship crashed in London.
Captain Defenestrator