Question: When did Erica and Harry switch eye glasses?
Question: If Erica arrived after Marin and Harry, why was she surprised to see someone in the kitchen? Surely she saw a car in the driveway. And where did that car go? It wasn't in any scene after Marin and Harry parked. Supposedly, they shopped for groceries and ate dinner the same day they arrived. Why did they change clothes so often? It seemed Marin had her black bathing suit on under her dress at the store but wore something different at dinner. Harry had three different shirts, Erica changed from a scoop to a turtleneck and Zoe seemed to put a sweater over her blue top while shopping but changed at dinner.
Answer: When they were trying to see what time it was the morning after they had slept together.