At 23:18, while Alison is asking the ghosts what they specifically want, Mike says "it feels like I should call someone", to which Alison replies "who are you gonna call?" - a shout-out to "Ghostbusters" of course.
Noel Fielding has an uncredited role in this. He's giving verbal support on the boiler problem.
Julian thinks the Internet is based somewhere. Dial-up internet was first commercially offered in the UK by Pipex the year before he died, although he must have dismissed internet as a fad.
The lion logo that can be seen on the steering wheel belongs to the France car maker Peugeot.