I recently wrote here about anachronisms in the Fudge series and as I continued reading the series to my daughter we found more. In the last book, Double Fudge, Peter is 12, only about 3 years older than he was in the first book, set in the late 1970s/very early 1980s. Yet inexplicably, his dad has a cellphone in this one and Harry Potter is mentioned. I know the last book was written way after the first, but still.... it drives me nuts!
One of my very first posts was about books that mention other books and I'm always on the lookout for more. The Fudge series has two that I noticed. One is, as noted above, the references to Harry Potter in the last book. The other comes in the penultimate book in the series, Fudge-a-Mania when Fudge makes a new friend named Mitzi and she insists that the book Tell Me a Mitzi (originally published in 1970) is about her! I'm really curious about why this was included. Is it just one of Judy Blume's favorite books? Or does she know the author?