you can ask about the way third and fourth year rotations are set up (how many hospitals will you be exposed to, how you're protected from excessive scut, who does your evaluations, etc.), what the top three specialties are that people end up going into, what the interviewer thinks is the one thing that makes their school so great/what they're most proud of with regards to the institution (a positive version of the "what would you change" question - you can figure that out by what they don't say). be sure to ask the students about the area, support for students having trouble in class, ease of research opportunities, if the early clinical exposure is actually valuable, etc. That's what I came up with off the top of my head, but I'm pretty sure there's a whole bunch of threads dedicated to this - I'd do a search.