The song that is playing on a stereo that Jen turns down and then back up at very end of the episode is Game of Pricks by the band Guided By Voices.
In 2013, Miranda (2009) aired an episode called The Dinner Party (2013) with a similar scene wherein the hostess asks everyone to behave naturally only to have them strike odd poses and then take up even weirder ones after she re-emphasizes being normal. Sarah Hadland was at both dinner parties (as different characters).
The Peter File joke is directly focused on the British pronunciation of 'paedophile' while the American is 'pedophile'. In fact, Moss thinks that Peter File should move to America.