I always found it kind of weird that no one ever mentioned that Cassie was black. It's not like I expected the fact that she was African American to be constantly brought up and talked about in the series (it would have been annoying if that had happened), but her skin color is mentioned one time through out a three year period. It seems to me that 13-16 year olds would have at least talked about it at some point.
Yeah, Ax's attitude towards Disabled people totally turned me off. I was like "AX is the best" then he got all freaky about that guy being a Vecol and I was like, "Ax is a pig", but then I guess he kind of worked it out.
I also found it strange that although Animorphs tackled a ton of heavy issues (for the age group) that they never did anying on Sexual orientation.