Well, aside from an eighteen-year-old lightbulb still in working condition (and I make no claim as to how Edison managed it)
You might not believe this, but I swear I have a working lightbulb down in my cellar that's been there and in use since 1978. Granted, I use it infrequently - about once or twice a week, and only for very short periods of time - but then, Liz wouldn't have used the lightbulb in the locked room for long periods of time either.
Jason comes across a suitcase full of clothes, and we're talking laundered, folded neatly clothes! Later, when Carolyn's curiosity about the room is finally satistified, I began to wonder that if I were her or Roger or anybody, wouldn't I question whose suitcase that was. Why was it packed and ready to go? Is this my father's suitcase? Whatever became of him?
By Ep #249 hasn't it already been explained to everyone that Paul's belongings were put away in that room, and hasn't Carolyn already refused to hear the "truth" of how Paul's departure from Collinwood came about?