Season 1, Episode 20 - Do No Harm is an episode that raises many more questions than it answers. It includes a back story about Jack.
We learn that Jack has saved the life of a woman named Sara in an automobile accident and in the course of her recovery they have fallen in love and intend to be married. Whether Jack and Sara are actually pronounced man and wife was not answered in this episode. Nor did we yet know has happened to Sara since Jack has never mentioned her on the island, nor does he wear his wedding ring.
The location where their wedding was filmed was at the world famous Kahala Hotel and Resort, located at 5000 Kahala Avenue just east of Diamond Head. This is a beautiful resort which you can read more about in our review of the resort.
The wedding scene was filmed at the wedding gazebo on the east end of the property near the shoreline.
View a Google map of this Lost location.
View a screenshot of this location from ABC's Lost.