Another thing that you don't get to see in the show is how big an asshole the Mountain is. That dude might be the most disgusting piece of shit in the whole story. Basically, all he's done this whole time is go from town to town slaughtering innocent people. One of his men told a story about him that basically went like this:
After the joust that he lost in King's Landing, the Mountain and his boys went to an inn to drink. The innkeeper was very cordial and took good care of them, but the Mountain was still pissed about losing the tournament. So the innkeeper's daughter was helping out, and the Mountain's men kept fondling her. Finally, one basically put his hand down her shirt and tried to force her upstairs. The innkeeper begged the Mountain to stop his men, so the Mountain told him to bring his daughter over to him. He looked at the chick and said "This is the whore that you would trouble me over." To which the innkeeper said "She's my daughter and she's not a whore." The Mountain tossed him a silver coin and said "She he is now." He then ripped the girl's clothes off and fucked her at the dinner table right in front of the father. After he was done, he let each of his men go. Then he asked for change because he said the chick wasn't even worth a sliver coin, and the innkeeper actually had to give him a bunch of copper coins to make up the difference.
That's the most fucked up shit I've seen so far in the story.