The head of lettuce that Frasier (Kelsey Grammer) kicks over to Regan (Gigi Rice) did not fall out of her grocery bag. You can see that it was rolled over to Kelsey Grammer from below the camera at the exact moment that the other groceries hit the floor.
During the opening credits, as Frasier sits in Café Nervosa, he is wearing a wedding ring. It disappears soon after.
Daphne massages Mel's back while wearing her engagement ring. Massage therapists normally remove jewelry on their hands and wrists to prevent chafing.