oh, in the second book, Visser Three picks up a cat carrier with a cat inside and choke-holds Chapman, when it's later indicated that Andalite arms are very weak (he can't even squish a Yeerk in his hand in book #29)
The nature of the Yeerk population--in book #1, V3 indicates that they'll need to breed more Yeerks to infest all the humans ("With this many hosts we can spread throughout the universe, unstoppable! Billions of us. We'll have to build a thousand new Yeerk Pools just to raise Yeerks for half this number of bodies." p. 36), while in later books, especially the Hork-Bajir Chronicles, it seems that within the Empire you have to be "selected" to infest a host, like there's more Yeerks than there will ever be hosts.
First, Alloran was described in TAC as being very well built, his arms being thicker and stronger than normal Andalites
Second Many Yeerk Pool ships are still out there finding and taking other species, then there's also the fact that the Yeerk homeworld is under a blockade, so they can't ship 'em from home.
second continued: the host selection was because before Earth, they only had small numbers of Ged and Hork-Bajir hosts compared to Yeerks, but then add 7 billion hosts to that number, and I'm sure that more than overwhelms their numbers that are not currently confined by the Andalite blockade.
Of course, it's done in vague enough language that it's possible to argue either way, but I really think she fully intended for Elfangor to have an Andalite family before she retconned him being Tobias' dad. I've only read the first two and a half books, but I've come across a few more errors, let me see...
K.A. had intentionally linked Tobias and Elfangor as father and son from the very beginning, "We all looked at each other. All except Tobias, who never took his gaze off the alien." and,
"We ran. All but Tobias, who knelt beside the Andalite and took his hand. The Andalite
pressed his other hand against Tobias's head. Tobias rocked back, like he'd been shocked.
Then he, too, was up and running, stumbling over the loose junk and potholes of the
construction site."
She hinted at a more-than-curiosity connection between them from the get-go.