After Samantha first see's Darrin in the mirror, when she turns and walks away her shadow moves across Darrin's lower body in the reflection.
Wardrobe goof: Towards the end of this episode, Samantha and Darrin sip cocktails while sitting on the living room sofa with Darrin's feet resting on the coffee table. The soles of Darrin's shoes show significant wear, and are covered with unsightly marks from sloppy shoe polish touch-ups. Apparently, Darrin's feet being on the coffee table was not written into the script and/or the wardrobe department never imagined the soles of Darrins's shoes would be so prominently displayed in the scene.
When Frank and Phyllis Stephens are driving home in their car, there are mature palm trees lining the street along which they are driving. These types of palms would not grow as street trees in New York, where the characters live.