I wouldn't say I had "curveball questions" but my faculty interviewer asked me some more challenging questions such as "How can you see yourself helping solve the big issues/inequities within our current medical system in your career?" (not word for word but you get the point). So I'd prep for some hard-hitting questions with broad answers like that. But it didn't feel like I was being challenged - it was a very relaxed convo and they just seemed genuinely hopeful for the future generation of physicians and were curious to hear my thoughts. My student interviewer asked me a lot of situational questions and brought up some specifics from my app, so just be prepared for some MMI-esque questions depending on your interviewer (again, they were also very chill, so it didn't feel challenging).