Whether to address weaknesses in your application during the interview is a difficult topic. Generally, what I recommend is as follows:
1. If you have a mild weakness (one mediocre grade/evaluation), there is no need to bring it up with the interviewer.
2. If, on the other hand, you have a major weakness (very low MCAT/failed the USMLE, large chronological gap, etc.) then you are better off addressing the issue head on. Think of the politicians who are caught in scandals: Those that 'fess up early manage their problems. Those that don't let the press interpret them. (I'm not saying that a weakness in one's application is equivalent to some politicians' misconduct; I'm just using this as an analogy.) If you have a glaring problem, go ahead and confront it head on. It will demonstrate integrity and will allow you to mold the admission committee's perception.
For individualized mock interview assistance, contact me. I am booking 2-3 weeks in advance, but I try to squeeze in clients sooner when I'm able.