Red Light, Green Light - S1-E23
Continuity mistake: When Dave sees Darrin's ad for the community meeting, he suggests a couple of changes, one of them being to add a line saying "and bring your friends". But the ad was shown in close-up shortly before Dave's arrival, and there was already a line saying "Be sure and bring all your friends". (00:13:35)
Answer: The original diamond and white gold heart necklace was given to Elizabeth Montgomery by her then real-life husband, William Asher, who also directed the show. She wore it in nearly every early episode. When the necklace was lost or stolen about mid-way through the series, Montgomery had two replicas made from rhinestones. She wore either one of those for the rest of the show's run.
raywest ★