Orpheus in the Undergrowth - S2-E2
Continuity mistake: When Rosemary finds her second bunch of smooth ink cap mushrooms and picks one, then declares, "Fungus Ferguson. My old college professor," who will be able to tell Rosemary what is special about smooth ink caps - this has been bugging Rosemary for days - and then grabs her cardigan without dealing with the mushroom in her hands, which is no longer to be seen.