On page 212 of the 1991 Corgi Paperback edition of "Good Omens" by Terry Pratchett and Neil Gaiman, on line 22 it reads:

"Agnes leafed through a battered card index in front of her."

This is a pretty major slipup because the character Agnes (Nutter)is not a character who is alive in the time in which the book is set. She is a witch who was burned at the stake in the 17th century, and the autor of the book of prophecies, "The Nice and Accurate Prophecies of Agnes Nutter", around which the story is centred, and is therefore only ever refered to in the past tense.

The charachter name used should have been Anathema (Device), A distant decendent of Agnes', who now owns the afforementioned card index of prophecies, compiled from Agnes' book.