The first run of the pilot's feast scene included Jaime and Ned talking about the Mad King, Aerys II Targaryen, and how he executed Rickard and Brandon Stark.
Instead of cramming this into the pilot, Benioff and Weiss moved the exchange to the third episode of the season, "Lord Snow." That way when Ned and Jaime speak bitterly of the Mad King and Ned's father in the throne room, it helps contextualize the events of Robert's Rebellion.
Given how much of the first season of "Game of Thrones" relies on an unfolding understanding of Robert's Rebellion and the way it impacted our various lead characters (Ned, Cersei, Jaime, Catelyn, and Littlefinger, to name just a few), it's no surprise that Benioff and Weiss first tested out the possibility of using flashback scenes.
One of the most legendary aspects of the unseen pilot is a flashback scene that showed Ned's father and brother killed on the orders of the Mad King. A small flash of this scene made it into at least one of the early "Game of Thrones" promotional trailers released by HBO.
In the footage, which lasts barely a second, a man who looks an awful lot like Ned Stark is struggling against a rope tied around his neck. Blood covers his face, and he's clearly in anguish. In the blurred background of the shot we can see the Iron Throne and a blond king upon it.