LOL I did this years ago & when I googled "questions on residency interviews preparation" most of what I found suggested
to study and have something to say about current/recent important changes/trends in practice of medicine
if you haven't done it do it, in an evening you can appear like you know WTF is going on
just be careful with political stuff/controversies
I said something like, "Like many docs from a public health standpoint and a sense of altruism I think policy that promotes more preventative care and gets more people seen by their providers is a good thing if not without challenges. With the physician shortage and limited resources, stewardship of resources and EBM becomes more important and challenging than ever. Who gets seen, how much gets done, and who pays, always the shifting target. How do you think Obamacare has effected practice here?" Could lead to a discussion of the patient demographics at the hospital, public health in the area, insurances there, social support systems ancillary services etc etc.
Diplomatic answers, try to see both sides of the issue and that whatever you say on its face is a given. You don't have to turn it around to a question for the interviewer, not trying to make this an interrogation. Just ideas for how to appear informed, engaged, poking your head up, big picture, etc.
Time to poke your heads out of the med textbooks and start reading more SDN, blogs, AMA & ACP email bulletins, etc. Try to look like you get that your job is shifting from "getting the right science factoid answer" to riding on the bureaucratic **** wave that your job is about to become.
TLDR;
part of good prep for residency interview is googling what you outta google
careful with politics