Director Adrienne Shelly was murdered shortly after the film's completion. Keri Russell was called in to record a director's commentary for the DVD in her place, recounting the on-set creative process and decisions that went into making the film.
The scene where Jenna and Earl argue in bed originally concluded in a sexual encounter that star Keri Russell described as "kind of rapey." While filming the scene, Jeremy Sisto's sympathetic delivery of the line "You're my sweet thing" caused director Adrienne Shelly to reassess her original concept of the character, and she changed the scene on-set to end with Earl quietly going to sleep.
"Waitress" is currently being made into a musical. It is having its world premiere at the American Reperatory Theatre in Cambridge, Ma. It is directed by Tony Winning Director Dianne Paulus and features a score by Sara Bareilles.  It has since made it to Broadway. 
In the film, Nathan Fillion and Darby Stanchfield play husband and wife. On the television series Castle (2009), in which Fillion plays the title role, Stanchfield has a recurring role as the first of his two ex-wives.
The trivia item below may give away important plot points.
Old Joe's check was apparently for $270,450, although the cursive total is partially covered by a thumb and the digits are off screen. (If you have zoom and freeze frame you can see the first part of the cursive writing when she first starts opening the check.) The amount was obscured on purpose through these methods and quick editing, according to the DVD commentary, in order to help avoid making the film seem dated in any way. The prop department, however, never did get the check quite right; Joe's address on the check is seen as "Box 12, Rural RT. 83, Southern USA."