"No, by your logic if this is a dream we all wake up eventually, yeah?" Amy wasn't going to let Arthur off that easily. He'd held a gun to her and forced her to dream share. She was upset with him and worried and he wasn't going to shake her off that easily.
"So tell me: if we went back to a dream within a dream would your die still work or wouldn't it? I know you're freaked out by the moving buildings. Ignore that part - just for now. What else would clue you into being in a dream?"
Amy reached forward and grabbed his suitcase holding hand. "Your die is right, Arthur. Waking up won't get you out of here. There's another way and the Doctor and I are working on it. You want out you're going to have to stop waving your gun around and listen."
She paused, "Plus, you still owe me an apology. A big one."