The water level of the Brita pitcher that Charlotte is holding in the kitchen when she is talking to Harry goes from very low to midway from one scene to the next.
Inconsistent.
When Carrie is sitting at the table talking to her publisher at the book store. The same woman in the gray sweater and black skirt walks by twice.
While playing mixed doubles, Herbert is serving to Harry on "match point", Charlotte cuts in front of Harry to return the serve and supposedly win the point. However, only the person being served to (Harry) is allowed to return the serve - the point would therefore be awarded to Herbert and Lisa.