Continuity mistake: Minnie gives her the necklace with the tannis root inside and Rosemary holds the chain between her thumb and first two fingers. In the next shot the chain is draped over her fingers. (00:32:15)
Continuity mistake: At the beginning, Barbara finds a corpse at the top of the farmhouse stairs with its face partially eaten away. Later, when Ben drags the corpse into another room we get a fleeting glimpse of its face and it shows no sign of decay of any sort.