See this blog from the Director of Admissions: http://tuadmissionjeff.blogspot.com/2010/08/applicaiton-is-here-now-what.html?q=Vanderbilt. It basically says are completely sunk… if I were you, I would take a chance and do the following: call up the Admissions Office and let them know you made this mistake and that you’d like your essay back so you can correct it. It would show a remarkable maturity and integrity that just might get you some favorable notice. Given Jeff Schiffman’s blog, I think you have nothing to lose. If you do get in, please PM me to let me know. Best of luck to you!