There are significant disadvantages, especially in medicine, if you go to a foreign university but plan on working in the United States.
Yes, however, medicine and sciences are the same everywhere, it's just some time to learn the regulations as I understand for most things. if you want to move to another country, starting by going to a foreign university (to see if it would be a good choice to move to and for staying there for a few years will further citizenship process. The only other big disadvantage is student visas, it can be a hassle.