At first there doesn't seem to be any particular reason why Arbron picks a yellow VW Bug to convey Jake down to meet the Free Taxxons. But then you remember that when Arbron first became a Taxxon nothlit, the Living Hive brought Elfangor down to him in a yellow Mustang. Knowing Arbron's humor, he probably enjoyed the symmetry.
One of the things Ax finds amusing about humans think telephones are more advanced than the Internet. At first, this seems equally silly to the reader, but then you realize that Andalite telephones have to transmit Telepathy, not sound.
In The Alien, Ax fixes Marco's dad's programming. This makes little sense at fist, since human computers should be completely different than Andalite computers... until you realize that Elfangor exchanged ideas with 'Bill' and 'Steve'. And even said he had to use simple terms like "WINDOW" to explain advanced concepts!
In Visser, it's said that Hork-Bajir are a Class Three species because they are not numerous enough and they can't be quickly bred. That means they breed the creatures they take as hosts. Obviously, this is not explored in the series, but in the books where the horrible future of Yeerks completely taking over humans is shown, this means that aliens in those humans' brains are making them have sex with each other so those aliens can conquer the galaxy. Want to take the horror a step further? Yeerks have really poor senses in their natural bodies and get drunk on the senses of their hosts, they explore them and indulge them for pleasure. Think about how eager just normal people tend to be regarding having sex, because it feels so good, now add in a sensation starved parasite in charge of the decision making process and thousands of others in the exact same situation for them to experiment with. And the host has absolutely no say in it whatsoever but still has to experience it. You'd be getting raped until the Yeerk gets bored of it, if ever, and possibly they may not care about the age of the hosts involved.