When they look out the window, they’re facing the square, but the layout says the windows should be on the other side of the pub.
A lot is just to be able to accommodate the practicalities of filming and to compose a pleasing image. Although you’re presenting a domestic scene theres a camera and track in the room and around 20 people standing behind it. The sets are shaped to represent a domestic scene but the actually have to work for the film crew.
This is more obvious in things like soaps because they have to film really fast. In a one off drama / movie you can spend more time removing various walls, filming reverse angles etc and portray a more accurate space but soaps are much faster moving, so you have to shape spaces more like a theatre set so that all the action plays one way and you can get two-way conversations in one take even if its on multiple cameras. In cinema you’d do take after take – close ups, wides, and each persons view point, moving the set, props and camera to compose each shot – it takes days.
Whats really fun is watching old episodes of Taggart where they don’t bother with any of that, no sets, just rock up in any room get the actors to play a game of sardines where they’re standing shoulder to shoulder taking to the backs of each others heads and get it all in one take so you can all get to the pub early.