The TV series:
- Crowning Music of Awesome: Earle Hagen's theme and episode scores (as well as averting California Doubling, the series eschewed tracking in music - like other shows from the same producers, every episode had an original score, which was by no means common for 1960s TV).
The picture books:
- Surprise Difficulty: Some people might be surprised that, in spite of the target audience being children, the riddles can be shockingly difficult and even stump many of the parents who were trying to solve the riddles with their kids.
- Visual Effects of Awesome: Yes, in a children's book series. The grand majority of the books were written before Walter Wick moved to digital photography...which means that, yes, every single picture was completely real and done by hand, with zero photo editing. He even has a series of behind the scenes features on his web site detailing how he put together quite a few of the harder-to-explain pictures.