Also make sure to understand how often classes are offered…some aren’t offered every semester or even every year. This availability isn’t always obvious in the catalog, you have to go to the listing of current courses for the current and previous semesters to get at that (these are often public, but not always.) Prereqs will be more updated in the course registration system too.
Another thing that can be interesting to do is to look at what types of research the profs in the subject areas of interest are doing and see if there is a better match that way. Good luck!