You might already know that Game of Thrones filmed a pilot that never aired. With different actors playing Daenerys and Catelyn, and a few other changes. Not much is known about this earlier Thrones pilot, except for a few hints — but a copy of the script was posted online. Here's all the scoop about the Westeros you never saw.
The original Thrones pilot was filmed in the fall of 2009, directed by Thomas McCarthy in Scotland and Morocco instead of Northern Ireland, Malta and Croatia like the aired episode. A few scenes from this pilot made it into the aired pilot, but most of it was scrapped and redone. In 2011, producers David Benioff and D.B. Weiss told us that they watched this version of the pilot with their friends who hadn't read the books — and at the end of the hour, their friends had no clue Jaime and Cersei were brother and sister.