I was just assuming it was just me that had never noticed those windows
There's windows at the side of The Rovers?
You can just make out the upstairs windows on the side of the Rovers in this pic of the outdoor set circa 1982:
http://i43.tinypic.com/b63c3l.jpg
But in a more recent shot they've added a window and door on the ground floor (not to mention another viaduct!):
http://i43.tinypic.com/ila8v9.jpg
EDIT:
On looking again, the door may be visible on the first pic, but mainly hidden in the recessed part of the wall.
that side door has always been there but when Liz used it it was the first time it's been used on screen (it's meant to be the kitchen door despite looking like it goes straight into the bar (which it does)
the upper side window in the old pic is a double sided window which is also visible from the rear yards, it's purpose is to create the onscreen illusion that the building goes down the side as well, when in fact it's just a wall with false windows in it. In the rovers yard there is another false window in this side wall but we rarely see it on screen as it's opposite the smoking shelter so effectectivly behind the camera
the side windows I mentioned suddenly appeared in the indoor set either side of the fire place (one of them technically being in the same place as the previously mentioned door on the outdoor set
maybe if they move the corry set to media city they'll have the space to create a more visually convincing out door set
talking of the outdoor sets, how often did they use the rear yards on the original set, onlty time I remember is when Elsie's house caught fire and Hilda was outside hanging washing and could smell burning (stan was on the outdoor lavvy)