As an interveiwer, I've written about this before, but one actually has to work at getting rejected. For many schools, being interviewed is the same as getting accepted.
We've wait listed people for having too many poor grades, a poor MCAT history (ie, 19, 20, 20 then 26...we like the avg MCAT score to be >24); being too nervous at interview; not fully understanding what they're getting into; not having enough ECs [like, none at all!]; thinking that osteopathy is identical to allopathic medicine (they're not, and you should know why); being interested in a lucrative specialty; being more interested in procedures than people; being blabbering idiots; not being able to think on their feet; poor verbal English skills (if I can't understand you, how will a patient?); being too immature; doing all of their pre-recs one at a time over a multi-year spread at CC's; and not being interested in the interview (looking bored, etc).
We've rejected or low-wait listed people for having bad LORs (rare); having a felony conviction or multiple misdemeanors (multiple DUI much more serious than a one time event); outright lying about their file or background; being too immature (I had a girl start crying in the interview once); overdominating the conversations (we rejected one 4.0 person because she wanted to answer other interviewee's questions); addressing the interviewers by their first names; never making eye contact with any of the interviewers; snapping gum during the interview; and for trying to get back into medicine after being kicked out of other medical schools.
There are probably others, but that's all I can think of on the fly.