Who should I contact if there is an error (not major, but not as minor as a spelling mistake) I recently discovered in my application?
First, calm down. The world will not end tomorrow. Second, you can easily use their email system from this site:
http://admission.stanford.edu/contact/ where you can indicate the reason for your email. Also, you can call or fax the correction directly to the office of admissions:
Hope this helps B-)