Doctor Who Series 10: 14 Easter Eggs & References You Might've Missed In 'Smile'

7. The Seeds Of Doom

Elsewhere in the episode, the Doctor and Bill discover the gruesome fate of the early colonists: they have been turned into fertiliser by the Vardy. In another nod for Fourth Doctor fans, this recalls 1976's The Seeds of Doom.

In that story, plant-obsessed villain Harrison Chase dispenses with those who cross him by shredding them into mulch in his giant compost machine. Spoilers - at the end of the episode, Chase gets his comeuppance and is fed to the machine himself.