Plot hole: Darrin tells Samantha that Larry thinks the Stephenses are having a costume party. While Larry earlier had said that to himself when he looked through the Stephens' living room window, he never said it to Darrin. (00:20:45)
Hippie, Hippie, Hooray - S4-E21
Plot hole: Why would Serena need Samantha to zap her out of jail? Serena is a witch and very tricky.
Answer: Larry had been telling Darrin what it means psychologically that Samantha gave the coat away. Larry said giving it away meant she's happy being married but if she liked the coat it means she desires to be single and carefree. So when Darrin sees the coat, he immediately thinks Samantha doesn't want to be married and the fact that she twitched it means (in his mind) she wants to be a single, carefree witch again.
Bishop73