The hand that Captain Jack Harkness is so fond of and keeps safe, is The Tenth Doctor's hand from The Christmas Invasion (2005). The Doctor had his hand cut off in a duel but immediately grew a replacement hand.
Reference to putting bromide in the water supply to stop sex citywide. Potassium bromide is a sedative and anti-convulsant and its anaphrodesiac properties have been claimed since the late 1800s. Urban myth says that in WWII the British military fed soldiers bromide in their tea to suppress sex drives and that British boarding schools did the same all the time.
If one watches carefully during the scene when Jack and Gwen investigate the alley beside the nightclub, a pair of bare human feet can briefly be seen poking out of a trash can behind Jack's shoulder.
The ex-boyfriend wears a brown sweat suit with yellow an red stripes and an ASV sticker. Which means Armee Sport Verein and was the eastern german army sports club. This sweat suit was the standard sports suit there until 1989.