Fact File

- This episode features the largest number of supporting actors in any episode of Whovians - there are twenty-one possessed zombies throughout the episode.

- The character of Ellie is based on a friend of Hannah Celyn Grithiff's who is called Jen - who also has a brother called Liam

- The yellow car which appears abandoned in the middle of the road belongs to Assistant Director Teddy Smith; the driver is executive producer Matthew Ford. 

- Whilst the exteriors of the café scene were filmed at the Lookout Café in Cardiff Bay, the interior was filmed at Chapter Arts Centre in Canton.