In a very revealing podcast with the folks over at Empire, Iron Man 3 cowriters Shane Black and Drew Pearce talk primarily about the stuff we won't see in Iron Man 3, including scenes that were in previous drafts, as well as footage that was cut out of the current version. According to Black, they had to cut out almost 80 minutes of footage in order to get the film down to its current running time, with the original assembly cut coming in at three hours and 19 minutes.
One of the craziest scenes that was in an actual draft of the screenplay found Pepper Potts sleeping with Guy Pearce's Aldrich Killian after he seduces her with power, leading to him filming a sex tape of the two that he then goes and broadcasts in Home Depot. Yes, seriously. Not only would that scene have given us the most interesting piece of product placement in a summer blockbuster, but it may have also gone down as one of the craziest moments in a superhero movie ever.
Other things that were cut out according to Black and Pearce were different villains (Madden, Simon Krieger, Edwin Cord), along with MIT geeks that help Tony Stark out (including one "semihot Asian chick") and a massive car chase, which is the one scene both men wished they could've kept. Additionally, during the scenes shot with the little kid, there was one where he helps save his own bully when a water tower falls on top of him.
Oh, and the Downton Abbey stuff? That came from Jon Favreau.
You can listen to the entire podcast below (Black and Pearce come in at around the 45-minute mark), including spoilery stuff about the Mandarin, his tattoos, the ending and more.