When Harry and Erica are arguing outside the restaurant after Erica sees Harry with a young blonde woman her cell phone is in her hand in the shots where the camera is behind her, and not in her hand in the shots where the camera is behind Harry. Every time the camera switches she's either holding, on not holding, her cell phone.
When Marin and Erica are having the conversation on the steps on the beach, Marin's left hand alternates between being at her side and on Erica's back between shots.