Continuity mistake: Frazier and Marty go into the kitchen. Frazier gets out a blue bottle of water, uncaps it, puts the cap on the counter - and in the next shot we see him do the same thing again. He then goes into the living room and mistakenly tells Daphne he is going to pay for her wedding. She hugs him, and he is still holding the bottle of water. The next shot of her hugging him shows nothing in his hands, and when she lets him go, he whirls around and grabs his bottle of water off the bookcase.
Continuity mistake: Roz and Daphne are standing in front of the elevator talking about the wedding. Daphne is holding Frasier's choice of a bridesmaid's dress. In one shot, Daphne is holding it over her arm, but when she turns toward the door, with no time to change position naturally, she is holding the dress by the hanger.
Continuity mistake: When Marty comes into the living room, he puts the container of jerky down on top of the book on the right side of the coffee table. A few minutes later, when Donny takes a piece, the container is on top of the book on the left side of the table. No one went near it in the meantime.