In chapter 2 "And his motley crew", the sentence "In a gravitational pull of 9.98 meters/second his stance was unconsciously natural." Firstly, the "pull" exerted by gravity is an acceleration, not a velocity, so the units should be those of acceleration (or force if we wish to include Louis' mass), so it should read "meters/second-squared." Second, the value 9.98 is perplexing. On the surface of the earth, standard gravity results in an acceleration of 9.81 meters/second-squared, not 9.98, so either Earth's gravity has inexplicably increased from our time to the time that Ringworld occurs, or the gravitational pull at which Louis' stance is natural is not that of Earth's gravity, but rather slightly higher, why though remains a mystery....
In chapter 3 "Teela Brown" the galactic core explosion is briefly explained. Basically all the stars at the galactic core have gone supernovae and in 20,000 years the radiation from this will reach known space, necessitating evacuation. This is known because a man ventured close enough to the core and was able to report back using a FTL ship. However, if the light from the explosion is visible (that is it has reached the observer) then so has the deadly radiation. The ship would require some sort of shielding to allow the man to return with the images but if such shielding exists, then why is evacuation the only option? The man who traveled must therefore be dead and did not complete the trip (presumably the ship returned on autopilot), or he was a fiction and the ship was always autonomously piloted. But these issues are never addressed. There's a bigger problem with the galactic core explosion though, which is that it doesn't happen. The idea is that the stars are too close and cause each other to heat up, causing premature supernovae in turn causing a chain reaction of supernovae. But it doesn't work this way...
In chapter 4 "Speaker-to-animals", Nereid is referred to as "Neptune's larger moon." Implying that Neptune has two moons and that Nereid is the larger of the two. Neptune has 14 known moons, although as of Ringworld's publication only two of these had been discovered. However, of these two, Triton and Nereid, Triton is the largest, and this would have been known at the time of Ringworld's original publication. At only 340 km in diameter, Nereid is startingly small, and yet Niven writes of the alien race known as The Outsiders "Presumably they had evolved on some cold, light moon of a gas giant; some world very like Nereid..." Offering no explanation for how life might be presumed to evolve on such a tiny world. We can assume Niven meant Triton here when considered with the other mention of being the "larger moon".
In chapter 4 "Speaker-to-animals" we learn that Teela had two first loves: one who tired of her after half a year, the other who left her after getting a chance to emigrate. However, in chapter 5 "Rosette" it is written that Teela had twice been in love, and that she had twice been first to tire of the affair. While this need not directly contradict the earlier info (Teela may have been the first to get tired but chosen not to end the affairs), it certainly comes across that way, as the first time the information that Teela was in fact tired of the affairs before they had ended is completely absent. Since the information in chapter 5 is simply a retelling of what Louis learned from Teela in chapter 4, there is no reason for the two to be inconsistent. No new information has been revealed from Teela to shed new light on old information. Rather the same story is retold but now with a completely different narrative.
In chapter 6 "Christmas ribbon", it is mentioned that the Ringworld is spinning fast enough "to provide an additional centripetal acceleration of 9.94 meters per second." Acceleration is measured in meters per second-squared not meters per second. Later Louis Wu notes that this gravity is a touch less than that on Earth, backing up the earlier claim of a pull of 9.98 meters per second-squared. But why this differs from Earth's actual gravity of 9.81 meters per second-squared we don't know, and it appears to be an error.
Somewhere (I don't remember where) it is mentioned that a General Products hull reflects 100% of neutrinos. The Ringworld material reflects 40%. This fact is first presented as astonishing, with Louis Wu whistling. But in a universe where 100% of neutrinos can be reflected, why should a material that does worse than that be astonishing? Certainly it would be of interest as the mechanism is no doubt different, but it seems very unlikely to impress much. Also, the fact that a GP hull can reflect 100% of neutrinos would imply that the technology exists to shield against the radiation that would result from a galactic core explosion. So an evacuation shouldn't be the only option in the future.
In chapter 7 "Stepping discs", Nessus reveals that visible light lasers can penetrate a GP hull and kill the passengers inside. How a hull could be devised that can reflect neutrinos but not visible light is a little baffling. This implies that shielding for the galactic core explosion does not exist, which again implies that the discoverer of the explosion must have died on the trip.
For both the Kzin and the Puppeteers, the female sex is non-sentient, with only the males being intelligent. This seems beyond implausible. While dumb males could evolve alongside intelligent females, the reverse is almost certainly not possible. If the female is non-sentient, then what sexual selective pressure can there be? The sex with the scarce resource (eggs) evolves to be discriminating towards the sex with abundant resources (sperm). Understanding male/female in terms of eggs/sperm makes the prospect of intelligent males and dumb females seem only possible were it designed by males rather than arising through natural selection. Perhaps the Kzin and Puppeteers are both in fact smart female/dumb male species , but Louis Wu is such a misogynist that he can't conceive of this?
In chapter 8 "Ringworld", the Liar matches the spin of the Ringworld with 0.992g of thrust. Assuming 1g = 9.98 meters per second-squared as from earlier would put the acceleration of the liar at 9.90 meters per second-squared, less than Ringworld's 9.94 meters per second-squared acceleration, so it would not be matching the Ringworld's spin.
The sexism in Ringworld continues in chapter 21 "the girl from beyond the edge". We are introduced to a woman from the race of the Ringworld engineers. She comes from a crew of thirty-six, of which three were women. Louis Wu then says, "You might as well forget about her profession." From this we know that her "profession" was copulation with the men on the ship who did the real work. So there are the kzinti for whom females are non-sentient, the puppeteers for whom there is a non-sentient sex inferred as female (since others are referred to as him), and now the Ringworld engineers, an advanced race of humanoids who have built an implausible structure of unfathomable size, and seem to regard their females as little more than creature comforts. Now we could say that this is simply the way these aliens "are", and that we don't have to like it, it is presented as-is. The problem is that these aliens are purely the imagination of Larry Niven, so any aspect of them is either inconsequential or made to be so by conscious choice by the author. Here the author has consciously chosen to present three species for which the female sex is devalued relative to the male. One might defend the kzinti and the puppeteers by saying that the sentient sex may actually be female and that the referral to them as male is an error on the part of Louis Wu, an error that is then adopted by the author. But the author makes no attempt to correct or suggest such an error and has chosen Louis Wu's perspective through which to tell the story. So Louis Wu's view goes unchallenged and is therefore a reflection of the author's view. Again and again we are presented with devalued female sex. In the case of Teela Brown, much could be said about her unflattering characteristics and the fact that she is a she, and while her character is defensible in terms of the plot, it becomes indefensible because she is the only female on the crew. Her characteristics set her apart not only from Louis, but from the two aliens as well. In other words - females are more alien than genuine aliens! If Nessus was identified as a she or as gender-neutral, or Teela Brown was a counterpart to Louis Wu or even simply if kzinti females were sentient this would not seem so egregious, but taken together it paints an unflattering opinion of the female sex.
References
Niven, Larry. (1970) Ringworld. Toronto, Canada: Del Rey Books.
