Revealing mistake: After Lansbury makes her clothes start to move, her nightgown attacks someone and you can notice the strings that make the gown move.
Continuity mistake: When Von Aschenbach is dressing for dinner on his first night in the hotel, he makes a great show of placing a red, silk handkerchief in the breast pocket of his white dinner jacket. When he goes down to the dining room, the handkerchief is no longer showing.
Continuity mistake: When Gran first dangles down from the ventilation shaft, the slaver's key ring is too wide to fit through the opening. But when Jim loses his balance and Gran is jerked back into the cell, the key ring is suddenly much smaller than before.