Joe Fox's grandfather mentions that long ago, he briefly shared a pen pal romance with the store's previous owner, Cecilia Kelly (Kathleen's mother), and that they only communicated through letters. This may have been a reference to the movie's predecessor, The Shop Around the Corner, starring James Stewart and Margaret Sullavan, or possibly the famous book and the movie 84 Charing Cross Road of the same name, with Anne Bancroft and Anthony Hopkins as a female customer in New York and a male employee of the bookstore at that address in London.
Joe misquotes The Godfather: When Joe Fox and Kathleen Kelly first meet at the cocktail party, Joe says, "I didn't know who you were with," quoting the movie producer Jack Woltz. The actual line is, "Why didn't you say you worked for Corleone Tom?"
The scene where Joe accidentally closes the door of Kathleen's shop on the balloons was unscripted. Tom Hanks actually did that, and ad libbed the line, "Good thing it wasn't the fish." The director thought it was so funny that she kept it in.
Kathleen Kelly's bookstore in the film was based largely on Manhattan's Books of Wonder in Chelsea on 18th St. Meg Ryan worked the counter at Books of Wonder for a day as part of her preparation. Decorative props from the film can still be seen at the store.
At one point Michael Palin was to play a benevolent writer who frequently gave readings at Ryan's store. Although he filmed several scenes, they were eventually cut from the film.
Meg Ryan's character, Kathleen Kelly, uses a Macintosh PowerBook G3 "Kanga", (introduced 11/97), or a Macintosh PowerBook 3400c, (introduced 2/97) in the movie. The exact model she used can't be determined from looking at the outer plastic case, as both machines used the same plastic case.
The passage that we see Kathleen Kelly reading during her bookshop's story time to a group of kids (including Joe Fox's aunt and brother) is from "Boy: Tales of Childhood", an autobiographical children's novel written by Roald Dahl.
The song at the end of the film when they are standing on the bridge is "Somewhere Over the Rainbow". A clip of this song is played in the previous movie with Meg Ryan and Tom Hanks, Sleepless in Seattle.
The movie's opening and ending titles make use of commonly seen computer images of the time, specifically Windows 95/98. The ending title song, which begins just after the words "The End" appear on the screen, starts with and adaptation of the "startup" sound from Windows 95.
The location of Fox Books in the movie is actually the location of a real-life Barnes & Noble, on Broadway and 83nd street on the upper west side. The Barnes and Noble generated considerable neighborhood opposition when it opened in the early 1990s, as many feared it would drive a local bookseller, Shakespeare & Co. on 81st street, out of business. This is exactly what happened.
The New York previews were shown in the exact same theater (same building, same "room") that Meg Ryan and Greg Kinnear go into to see their movie, the Sony Lincoln Square 13 and Imax Theater.
Both Kathleen and Joe used AOL software to connect to the Internet. They were both using version 4.0 which was in beta testing mode when the film was being made.
Joe Fox (Tom Hanks) is obsessed with The Godfather, and frequently uses dialogue from it to shape his philosophy on life. In the Coppola Restoration Godfather DVDs, Alec Baldwin claims that Hanks and Rob Reiner are both Godfather aficionados who have been known to host viewing parties where the attendees do drinking games and quote famous lines while watching the film.