The final scenes were shot in Terminal 4 at JFK International Airport in New York City. Production was unable to close the area for filming, so it was still a working terminal. The people walking by Natalie Portman and Zach Braff are real travelers.
Zach Braff chose to not include a full love scene between him and Natalie Portman because he felt it would take the audience out of the movie too much. He wanted it to be implied and sweet rather than visual.
When Zach Braff sent the script to people, he would also send them a copy of the songs which would eventually be the soundtrack (which he handpicked). That is why on the actual soundtrack album, all of the songs are in the order that they appear in the movie.
On the commentary track, Natalie Portman admits she had never handled a vinyl record before making this movie. She had to be taught how to start a vintage "record player" properly for the scene in her bedroom.
The depiction of 'Zach Braff''s character working in a Vietnamese restaurant was from his own experience. Braff worked as a waiter in a French-Vietnamese restaurant when he auditioned for the leading part in the series Scrubs (2001).
In the scenes where Andrew, Mark, and Sam are walking together, Natalie Portman had a hard time keeping up with Zach Braff and Peter Sarsgaard because they are both so much taller than she is. She was out of breath after most takes because she had to walk so fast.
Zach Braff had to give a testimonial to JFK International Airport in order to film there. His testimonial was about how much he liked Terminal 4, the terminal used to film the final scenes of the movie.
Tim (Jim Parsons), the knight armor-donning nerd, speaks the fictional language Klingon, from the Star Trek series. Parsons would later play the intellectual, yet socially-confused and Star Trek-obsessed nerd Sheldon in the sitcom, "The Big Bang Theory".
The only song that does not appear on the soundtrack is "Orange Sky" by Alexi Murdoch, because the rights had already been sold to the WB to be used for Fox's The O.C. (2003) and its soundtrack. As well as "Love Will Come Through" by Travis, which was played in the trailer for the movie. The original version of "Such Great Heights" by Postal Service is also used for the film's trailer. A cover of this song by Iron & Wine can be heard in the film.
The high school Andrew asks Sam if she went to, Columbia High, is the name of the high school Zach Braff attended in New Jersey. Columbia High School also makes a brief cutaway-shot appearance as Andrew, Sam and Mark are riding to the quarry in the military vehicle.
Zach Braff wrote the majority of the script while he was in college, and originally titled it "Large's Ark". He tested the name on various messengers coming to his house during production, but none like the name. When he suggested "Large" no one liked it either. "Garden State" was well received. The original title still appears vestigially in the company credits, "Large's Ark Productions".
The movie was released on Wednesday, 28 July 2004, to eight theaters: three in Los Angeles, four in New York City, and the Maplewood Theatre in Maplewood, New Jersey. This was the home theater of Zach Braff (who is from the adjacent town of South Orange). He attended the Maplewood premiere, and his father, who still lives in the area, was at the theater for the film's first Friday and Saturday.
Zach Braff drew partially on knowledge from his mother, a psychologist, his stepfather, also a psychologist, and his step mother, a therapist, to give scenes involving mentions of psychiatrics and pharmaceuticals authenticity.
Noise pollution was an issue throughout the neighborhood scenes. Zach Braff stated in the DVD commentary track that birds and airplanes were the biggest problems due to the high amount of trees and filming so close to Newark International Airport.
The first public screening of the film was at a benefit in Detroit for a charity working with mentally challenged people. Members of the cast, specifically Natalie Portman and Zach Braff, were embarrassed and nervous about the word "retarded" being used throughout the film.
While filming the funeral scenes most of the extras were Orthodox Jews and prevented the crew from shooting on Shabbat and craft service was forbidden from serving any non-Kosher food on the property lines.
It was raining in every scene shot outdoors. Zach Braff described the weather as unusual in the DVD commentary saying in all of his years living in New Jersey he had never seen it rain so much in the month of May.
In the background dialog at the grave site, a character is trying to remember the name of the author of the novel, "Brave New World". The character ultimately concludes that the author is Aldous Huxtable - although the book was actually written by Aldous Huxley.
The Vietnamese restaurant in Los Angeles in the beginning is actually a Thai restaurant - Sea in Williamsburg, Brooklyn, New York. Walking through the kitchen the background voices can be heard conversing in Thai, not Vietnamese.
During the swimming pool scene (when Andrew cannot swim) the fog was not there for effect. The site was originally chosen because the Manhattan Skyline was clearly visible but it just happened to be incredibly foggy on the day of filming.