Schedule Slip: Blume wanted to do a sequel to Fourth Grade Nothing right away, but had tremendous trouble coming up with what it could be about, until as she describes it, the entire story of Superfudge suddenly popped into her head while she was in the shower.
In the first book, elevator buttons are presented as new technology. The newer editions still include it.
One of Peter's Christmas gifts in Superfudge was originally a calculator, a pretty big deal in 1980, but would seem really weird to any kid after 1990 or so. It's later updated to a check from his grandmother in revised editions. He also jokes around, asking for a stereo for his room in the original version, replaced with a laptop in the reprints.
In Tales of a Fourth Grade Nothing , Peter receives a baby turtle at his friend's birthday party. It's now illegal to sell turtles with shells less than 4 inches long as pets due to the risk of salmonella.