Most of the questions I was asked about were about my goals (what I wanted to get out of an internship, what I want to specialize in, my fields of interest, etc). I was also asked about my research experience and other unique experience on my CV. Some of the interviewers asked me about my strengths/weaknesses. I was only given a case once and it was pretty straightforward - they gave me the signalment and presenting complaint and asked me what diagnostic tests I would perform, what questions I would ask while taking a history, etc.