In my continuing Discworld quest I have finished The Last Continent, Carpe Jugulum, The Fifth Elephant, The Truth, Thief of Time.
I noticed an error in The Truth. I have a third or fourth edition paperback, so they had plenty of time to catch it. Gaspode was an informant and used the name Deep Bone. This is obviously a play on Deep Throat from the Watergate movie All the President's Men (read the book, it's not in there). Once in The Truth they refer to Gaspode as Deep Throat. I was a sentence and a half further on and then said, "wait a minute." and went back to check it.