* AssPull:
** The Hindmost reveals to Louis Wu in ''The Ringworld Throne'' that he has a quantum computer and the {{nanotech}}-based autodoc invented by Louis' biological father Carlos aboard his ship, without having mentioned them at all in the previous book.
** In ''Ringworld's Children'', Louis discovers that Teela became a protector on one of the Maps of Pak in the Other Ocean, then traveled to the Map of Mars on the other side of the Ringworld and pretended to turn into a protector ''again'' for Bram's benefit. Apparently, the only reason for this is to justify why [[spoiler:Wembleth]] lived near the Other Ocean.
** ''Ringworld's Children'' also introduces the concept of monsters in hyperspace that take time to catch and eat spaceships, in order to explain how [[spoiler:the entire Ringworld, 1 AU around its sun, can go into hyperspace without being immediately destroyed]].
* InferredHolocaust: The climax of ''Ringworld'' features kind of a doozy. They leave the Ring by [[spoiler: dragging their ship with shadow square wire. Thing is, they only have one end of the wire. The other is coiled up in a heavily inhabited city. Ever seen a high-tension cable break free? It can take off limbs. Now imagine ''hundreds of miles'' of ''razor sharp'' wire doing something similar...]] Apparently the author noticed this "small" problem (or a fan pointed it out) between the first book and the second, where Luis goes [[WhatTheHellHero What The Hell, Me]] (although since they get their end of the wire by retrieving it from the death-trap meant to kill them that the locals used it in, a karmic element is also present).
* {{Sequelitis}}:
** ''The Ringworld Throne'' and ''Ringworld's Children'' are arguably not as good as the first two books in the series because of the number of {{Ass Pull}}s required by the plot (see above). ''The Ringworld Throne'' also suffers from focusing primarily on the Fearless Vampire Slayers, with Louis spending most of the story only watching them over the Hindmost's video feeds.
** ''The Ringworld Engineers'' is also considered by some to be a step down in quality from the original book, mainly because of the odd hoops the characters are forced through to justify their new characterization in the story.
* TheyWastedAPerfectlyGoodPlot: While ''Ringworld'' -- and specifically its worldbuilding and the concepts it introduced -- has received generally positive reactions, some feel that one of the book’s main weaknesses is that it didn’t do enough with its own material. An enormous, diverse world full of worldbuilding possibilities is introduced -- which the main characters spent a significant portion of the first book flying over at high speeds, deliberately trying to avoid contact with it. Likewise, some feel that very little is explored in the way of the Ringworld’s history, societies, biodiversity and religions, despite the enormous potential these had: when these subjects are brought up, they’re usually discussed for a page or two and then dropped.