So I am thinking of taking mechanical engineering as an undergrad and aerospace graduate. If I were to go to an undergraduate school where they do not offer any aerospace emphasis or classes, would I be at a disadvantage in an aerospace graduate schools? Thanks
Probably not.
Take a look at the graduate programs that are interesting to you, and see what courses are required for admission, and once there, what courses are pre-requisites for the degree coursework.
So if there are no graduate requirements other than a degree in engineering or physics (I believe this is the case for Stanford graduate program), would I have a hard time learning this new stuff and would others with bs in aerospace have an easier time?