It always drives me crazy when a huge house like Collinwood and also the Old House are treated as though they only had a front door. There has been occasional mention of a back door, but anyone trying to sneak out (of either house) always goes the front way and has to try to pass everyone that's in the drawing room!
Now, here comes Nathan, living in, apparently, one room - and it's got a front and a back door!!!!!! At first I thought perhaps Noah was just to hide in the next room or a closet, but Nathan tells him to leave and there's a lock on the door, so presumably it's a real door to the outside.