The lovely old-time Electro Theater building also was used in The Day of the Clown: Part One (2008)/The Day of the Clown: Part Two (2008) as Spellman's Museum of the Circus.
Julian Bleach (Ghostmaker) goes on to portray The Nightmare Man in The Nightmare Man: Part One (2010)/The Nightmare Man: Part Two (2010) and Davros in Doctor Who (2005), joining the handful of actors that have appeared in all three erstwhile branches of the Whoniverse.
On their way to Chain Lane from the Electro Theatre, Jack and Ianto drive past Cardiff's St. Peter's Rugby Club, identified by the white goalpost at the end of the open green field beside Newport Road.
At the start, Andrew Garfield can be seen as an extra leading a date into the carnival. This may be the same character Frank from Daleks in Manhattan (2007)/Evolution of the Daleks (2007).
Camilla Power had worked with Tom Baker (The Fourth Doctor) in the BBC adaptation of The Silver Chair (1990) which Camilla Power played Jill Pole and Tom Baker played Puddleglum. The Chronicles of Narnia: The Lion, the Witch and the Wardrobe (2005) by C.S. Lewis was cited by Sydney Newman as one of his influences behind Doctor Who (1963).