In the closing scene where Tim and Daisy are dancing in the pub, the band playing is fronted by Simon Pegg's real dad.
Movie reference: when Tim carries Mike out of the TA offices, the song, the hat throw and the way he's carrying him is a direct reference to An Officer and a Gentleman.
The opening of this episode was originally intended to feature Tim having a conversation with a fictional character. Originally, this was intended to be Lara Croft, the heroine of the 'Tomb Raider' video game series, but the writers were not granted clearance to use the character. The scene was reworked to feature FBI agent Dana Scully of the TV show The X-Files (1993) and the producers had even considered approaching Gillian Anderson, (Dana Scully), to fill the role, but the scene was eventually filmed with a lookalike. Writer and star Jessica Hynes was going to dub the voice of Scully, but the scene was cut and never completed.
One of the white paintings is titled The Fifth Elephant which is the name of a Terry Pratchett comedy fantasy novel that was released the same year as the episode was filmed.
TV reference: When Daisy finally starts writing while on her bed, the theme music to Murder She Wrote plays in the background.