Worst epic science fail you have seen in sci-fi?

[Drashner1]

Did anything in Niven's Ringworld books say the Puppeteers were human sized? If they were transapients then each miles high building could actually be a puppeteer.

From various descriptions in various places (e.g., other Known Space stories, various artworks, Barlow's Guide to Extraterrestrials) and possibly the Ringworld books themselves (I don't clearly remember, I'm afraid), Puppeteers are actually a bit smaller than a human and their buildings are filled with apartments and communal eating and socializing areas of various sorts - mostly connected by stepping disks so that more space can be given over to such chambers and not 'wasted' on hallways, elevator shafts, etc.

The idea of transapients per se (and possibly of transhumanism, Singularity, etc.) may not have been 'invented' yet as a fairly well known concept when the books were written - I'm not sure on the dating of Vinge's original Singularity article vs the publication dates of the books. But basically it wouldn't really apply to the Ringworld setting as written (although it's a fun idea in its own right). Also, at some point in the course of the Known Space books Niven basically said that superhuman AIs develop to a certain point and then turn themselves off - and nobody in-universe knows why (and in his Draco Tavern universe, it's said that it might be better not to know why because then we might turn ourselves off too).

Todd