As Jack and Tosh are heading down the stairs in the club, the words "Bad Wolf" (the series 1 arc keyword for Doctor Who (2005)) can be seen in the graffiti on the wall at the top of the stairs.
On the door of the dance hall, there's a campaign poster for Saxon. This is the first official appearance of the "Mr Saxon" arc keyword for series 3 of Doctor Who (2005); except for a brief glimpse in a preview trailer, the keyword had not been seen in "Doctor Who" prior to this episode.
All the 1940s sequences were shot first.
This episode takes place in February 2008 and on January 20, 1941.
Bilis is shown taking their picture using a classic Polaroid Land Camera. Toshiko uses it as well to take an instant picture to plant for Torchwood to find of her calculations. This event is supposed to be taking place in 1941. Not only was that camera not unveiled until 1948, but instant film had only been invented one year earlier, 1947. However, Bilis is a time traveller and may have obtained it in the future.