When Rachel surfaces from the mere near the end, here eyes are closed. In the next shot, they are open.
Brunton explains the history of the manor to Watson, and says, "it is thought to be the oldest inhabited building in the country." He should have said "county", which is what is written the original short story. (There are many inhabited buildings in England, such as Windsor Castle, which are far older.) It could have either been copied incorrectly into the script, or misread by the actor.