Shut Up, Laura

For those who don't know, I'm getting married shortly.  Very small (by American standards) ceremony, everything happening in a single location so logistics should be easy.

However, my "Fretful Bride's Guide to Life" checklist says that I'm supposed to inform my best man (yes, I have a best man, move along) of his "duties" for the day of the wedding, things to take care of in case something goes wrong.

...but I'm trying to do the whole "Risk Management 101" thing, and am having trouble coming up with something that could go wrong that would be in anyone's power to address.  (Setting aside power outages, acts of war, etc.)  Seriously, what could go wrong here that my best man (or my father/mother/whomever) would actually be required to "fix"?  Some sort of...random seating chart accident?  Ummm....I'm truly at a loss here.

The only thing I can think of would be "You forgot to pay for blah blah blah", but at that point we get back to my Prime Directive of Risk Management: "Any problem you can solve by throwing money at it, isn't really a problem."