According to the DVD commentary, the scene where Jack gets back into his minivan and the minivan won't start was a happy accident that wasn't supposed to happen. The director thought it was a perfect beat and left it in the final cut.
When Kate is talking about how their lives changed, she says, "When you stepped in at the store" referring to when Big Ed had the heart attack, but it also refers to when Jack intervened with Cash at the convenience store, and his life changed.
The scene with Jack looking at his old book and cologne that Kate gives him back was originally supposed to have Led Zeppelin's "All of My Love" playing in the background but the song was too expensive to acquire.
In the scene where Kate is lying in the bed and Jack is asking her to remember him no matter what, Kate is reading a book called 'Being There' by Jerzy Kosinski. The book is barely seen in the screen but it has a connection. It is the story of Chauncey Gardiner, an enigmatic but distinguished man who emerges from nowhere to become an heir to the throne of a Wall Street tycoon. Similar to the storyline of Jack at that moment, as he tries to move into the investment firm from a tire salesman job.
At the beginning of the movie, Jack sings "La donna è mobile" from the Giueseppe Verdi opera 'Rigoletto'. In the opera, the song is sung by a womanizing duke who describes women as flighty and untrustworthy, when in actuality the duke is the flighty and untrustworthy one. This is similar to how Jack is at the start of the film: a wealthy, irresponsible philanderer who is blind to his own flaws.
In this movie Jack Campbell's life is changed after he makes a "business deal" with Cash over a lottery ticket. In It Could Happen to You (1994), Nicolas Cage's character's life changes after a deal with a waitress involving a lottery ticket.
The film location for "Big Ed's" was in Tarrytown, New York. The building was the abandoned home of "Sleepy Hollow Motors", a car dealership. It was not in Tarrytown, NY. It was in Sleepy Hollow, NY which was formally known as North Tarrytown, NY.