Continuity mistake: 1967: Barnabas selects a treasure from a jewelry chest while bad guy Jason spies on him through a window. Willie is supposed to put the chest away, but when Jason later breaks in to steal it, the chest is still sitting on the table in plain view, so Jason has to pretend not to notice it. The break-in scene is recapped the next day, only this time, the chest is no longer on the table.
Continuity mistake: 1967: "Dark Shadows"' taping schedule seldom permitted retakes. Consequently, hundreds of goofs ended up on the air. Perhaps the funniest of them all occurred in a scene inside the Collins mausoleum, where the late Louis Edmonds was supposed to say, "Some of my ancestors are buried here." What came out was "Some of my incestors are buried here." To his credit, Edmonds not only kept his cool, but laughed and corrected the mistake in character.
Continuity mistake: Over the course of many Dark Shadows episodes set in the year 1795, Countess Natalie Dupres' dark, distinct, three-dimensional facial mole changes sides from left jaw to right jaw, briefly vanishes altogether, then returns as a faint, painted beauty mark on her right jaw.