While you may not be able to prepare for everything, you can still do the best you can...
Call your mode of transportation (limo, shuttles, etc.) two days before the wedding, as well as the morning of your big day. You'd be surprised how much can get forgotten or f#$@ed up in two days. Confirm all addresses and times.
Not the Jackie Chan & Chris Tucker movie (I wonder what that guy is doing these days...) Anyways, always account for traffic or road closures. Even if you think you are in the clear, provide a backup route anyways.
Photo Courtesy: Zuza Fun