The interior of Harry's (Jack Nicholson's) house is the same townhouse used as Miranda Priestly's (Meryl Streep's) house in The Devil Wears Prada (2006).
When Erica kisses Harry in the scenes outside the restaurant in New York City, it was an improvisation by Diane Keaton. Writer and director Nancy Meyers liked it so much that she decided to use it in the final cut of the movie.
20th Century Fox declined to make the film, citing that the leads were too old.