An interesting conundrum I have had to deal with in making Rosehill Cottage from the film The Holiday is the fact that movie houses don't always look the same on the inside and out. The exterior of the cottage was built in Shere, England as a shell, while the interior was built on a soundstage. For the most part the structure matches inside and out, with a few exceptions regarding window placement.
Here is an interior view of the same wall.
Notice the small window in the staircase area? Doesn't exist outside. While this wasn't an issue in the movie since the rear of the cottage was never on screen, it becomes an issue for me. There is just no good place to install a window on the back of the cottage without it looking wonky.
Another glaring discrepancy happens in the upstairs bathroom. Here is a shot of the set.
There is a window built into the angled roof line wall which looks great on the interior, but magically disappears on the exterior. This isn't the only instance that dormer windows happen on the interior, but I'm not going to list them all.
My decision has been to follow as closely as possible the matching areas, but on the discrepancies go with what works from the exterior point of view.
By the way, if you're into movie houses like I am, you may want to check out this blog called Hooked on Houses. There are some great shots of many movie houses and their accompanying sets, as well as celebrity houses and others.