I applied Early Decision and I just interviewed yesterday. There arent really any trick questions at all. Know why MBA, why Columbia, why now, what you can contribute to the school. Aside from these core questions, you may be asked about unqiue details from your work experience (i.e. I was asked about a stint of working in Japan and what I learned from it), how you deal with teams, and the most difficult aspects of your job. My interview lasted about half an hour--I couldn't really get a good read on my interviewer though. I'm not sure to take this as a bad sign or not, but I guess I'll find out soon enough. I would definitely recommend checking out the ClearAdmit and Accepted.com
interview reports if possible. Hope this helps!