In the opening credits, as Samantha Morton is driving through the countryside, the maroon estate car starts off being a Volvo 244, changes to a Volvo V70 and back to the 244 again as they arrive at the church.
The burned Bible found on the communion table towards the end is the CSB translation, which was first published in 2017. The Bible is supposed to have belonged to one for the girls who disappeared in the 1970s.