Candidates are often skeptical about whether or not MBA Admissions Committees will believe their stories. After all, is there really someone available to corroborate that you were the difference-that you had that innovative idea? The response to this concern is pretty simple: if it actually happened, you do not need to worry about your credibility. You just need to write about your experience with sincerity. If you can offer the details surrounding the events as part of a narrative, the story will unfold logically and truthfully and will have its desired impact. Conversely, if your story is basic and vague, it will not come across as compelling (regardless of its veracity).
An equally important point is that you are innocent until proven guilty. The MBA Admissions Committee is not assuming that you are a liar and reading your applications seeking proof of facts that are in doubt. They are taking stories at face value, recognizing that truth is stranger than fiction and that strong candidates will stand out on the strength of their experiences.
In addition, if you accomplished something truly remarkable, you can always ask your recommender to emphasize this in his/her letter. This does not mean that the Committee is seeking proof and that if something is not highlighted in a reference that it will not be believed. Still, your recommender can play an important role in legitimizing certain accomplishments.