Puzzle in Dracula room
Press the buttons on the mirror in Dracula's room in the following order to solve the puzzle: 6 (lion),7 (girl below line), 10 (goat).
Inventory items
Give inventory items to NPCs that you encounter to learn how they are used.
Cigarette lighter
The cigarette lighter looks like an old nine-volt battery.
Keys
Keys are not completely utilized until they disappear from your inventory. If one still appears, it still has a use at some point in the game.