I’ve read Heinlein’s Red Planet three times, starting at age seven or eight, and each time I soon forgot most of the plot. One thing that stuck with me was that the school’s new head signaled his evil by ordering the boys (at their own expense) to paint their space-helmets a uniform brown, in place of tiger stripes and other fanciful personalizations; I think that helped trigger my early interest in heraldry!
Another random bit that stuck with me is the place-name Charax, which I took to be a crude approximation to the Martian name, said to be very hard for humans to pronounce with its “triple gutturals”. Today I learned that Charax was a Roman camp in Crimea.