Jenny Beckman, the name mentioned at the start of the film, was a real girl who dumped one of the screenwriters, Scott Neustadter. Summer is based on this girl, and the film's screenplay is based on their relationship.
According to the DVD commentary, one of the film's writers estimates that 75% of the film actually happened to him.
The film's blue-centered color scheme was designed to bring out Zooey Deschanel's eyes.
When Summer returns to her ice cream-selling job, Tom can be seen waiting in line.
The studio never considered including the documentary about love in this film, and even went so far as to tell director Marc Webb not to shoot it. The audience's reaction during the first test screening convinced them otherwise.
Red is deliberately not used in this film, and the color blue is generally used to represent love or happiness (Tom dancing in the street after summer first arrives, etc.). Red makes a single appearance where a small red origami bird can be seen in Summer's apartment. It finally appears one last time when Tom meets Autumn, and her blouse is red.
Zooey Deschanel chose her own song for the karaoke scene: Nancy Sinatra's "Sugartown."
Summer breaks up with Tom on day 290 and gets married on day 476, a difference of 186 days. Roughly estimated, Summer got married six months after breaking up with Tom.
Around the time the film was released, director Marc Webb shot a short video for the Internet featuring Zooey Deschanel as Sid Vicious and Joseph Gordon-Levitt as Nancy Spungen, referencing a conversation in this film.
Paul says "humjob" instead of "blowjob" to avoid an R rating.
There is a fan theory that the final conversation between Tom and Summer on the park bench is entirely imagined by Tom and never actually happens. Even Joseph Gordon-Levitt has said he believes it is more a scene of Tom finding inner peace than actual reality. If this is true, then Day 408 (when he learns at Summer's house party that she is engaged) is Tom's last time seeing Summer.
The black-and-white films Tom watches at the cinema are parodies of films directed by Ingmar Bergman.
The narrator states that Tom meets Summer on January 8. Since it is 500 days, Tom quits Summer (and meets Autumn) on May 23 of the following year.
In the original screenplay, Summer was depicted with her yellow hair cut short to create a more summer-like personality.
The documentary about love was actually much longer and included the views of Summer, Rachel, Millie and Tom's mother.
The screenplay for this film was on the 2006 Black List, a list of the year's "most liked" unproduced screenplays.
This was the first feature film by director Marc Webb, who mainly directed music videos.
Ian Reed Kesler, who fights with Joseph Gordon-Levitt in the bar, is listed in the credits as "an actual douche."
During the office party, Summer and Tom begin talking about the validity of love. During the conversation, Summer mentions Johann Wolfgang von Goethe's "The Sorrows of Young Werther." When the idea of Tom singing comes up, Summer says: "I nominate young Werther here."
When Tom first enters Summer's apartment, the camera focuses on a bowler hat with a green apple on it. This resembles "The Son of Man," the famous painting by René Magritte, one of Summer's favorite artists.
On the screens showing the day numbers of the relationship, the coloring and "mood" of the background image change to reflect the state of the relationship. Good days are brighter, bad days are darker.
The New Hampshire Greeting Card office and Tom's apartment were shot in the same building.
The song playing when Summer first comes to Tom's apartment is Jack Penate's "Have I Been a Fool," and its lyrics are "A kiss is just a kiss, I think that's what fools say."
Joseph Gordon-Levitt wears T-shirts for Joy Division's "Love Will Tear Us Apart" and "Unknown Pleasures," and The Clash's "London Calling" album.
Tom and Summer love the band Bananafish, which briefly achieved national fame in the 1980s. The band took its name from J. D. Salinger's first "Nine Stories: A Perfect Day for Bananafish." Zooey Deschanel was named after another Salinger story, "Franny & Zooey."
In the first draft of the screenplay, the film was set in San Francisco.
The Smiths' "Louder Than Bombs," Jesus & Mary Chain's "Psychocandy," Public Image Ltd.'s "Album," New Order's "Power, Corruption, and Lies" and Pixies' "Doolittle" can be seen in Tom's childhood room.
Joseph Gordon-Levitt's character says: "It sucks, why is it that pretty girls think they can treat people like crap and get away with it?" In 10 Things I Hate About You (1999), Gordon-Levitt's character says "You know, just because you're beautiful doesn't mean you can treat people like they don't matter!"
Tom repeatedly associates the song "She's Like the Wind" with Summer. This song was first recorded for Dirty Dancing (1987), in which Jennifer Gray played the "she" sung about by Patrick Swayze. Clark Gregg, who plays Tom's boss in this film, married Gray in 2001.
The cover of Steven Patrick Morrissey's first album "Viva Hate" can be seen in both Tom's and Summer's childhood bedrooms.
The Ringo Starr music album Tom shows Summer at the vinyl store is his 1981 release "Stop and Smell the Roses."
The adult film titled "Sweet and Shower" that Tom and Summer rent is a fictional film and does not exist in reality.
The film takes place in 2006-2007 (the narrator says at the end of the film that May 23 was a Wednesday. The most recent year in which May 23 fell on a Wednesday was 2007). However, the email message Summer sends Tom on day 303 is dated May 7, 2008.
The narrator (uncredited in the titles).
The scene in which Tom and Summer play with the furniture in the store is not in the script. In the script, while Tom and Summer are at dinner, Tom makes fun of another couple and Summer refers to him as judgmental. The callback moment is similar because she had previously been willing to join Tom in mocking another couple.
Zooey Deschanel and Joseph Gordon-Levitt also appeared in Manic (2001).
After Tom and Summer break up and Tom leaves the greeting card company, a new employee is shown sitting at his old desk. The employee says to his boss: "What is this, Solitaire?" This can (potentially) be seen as a reference to Summer's preference for being alone.
During karaoke, Summer looks up Tom "Young Werther." This is a reference to The Sorrows of Young Werther, a German novel about a man hopelessly in love with a woman who does not feel the same way. The reference foreshadows Tom's unrequited love for Summer.
The film was shot during Matthew Gray Gubler's (Paul) hiatus from the series Criminal Minds. While filming this movie, Gubler seriously dislocated his knee; not on set, but while dancing in his free time. His injury was severe enough to require him to use a cane for more than six months, and when he returned to the series, his injury was written into the script by having his character Dr. Spencer Reid be shot in the leg to explain the continued use of a cane.
Jean-Paul Vignon originally narrated the Sweden scene in French. In the final version, Jonas Åkerlund narrates in Swedish.
For the Italian version, Summer was renamed Sole ("sun"). The name of the girl Autumn, whom Tom meets near the end of the film, was changed to Luna ("moon").
This film appears to have been influenced by the British romantic comedy Starter for 10 (2006). The protagonist of both films is a young man looking for love in the wrong places. Both protagonists are personally influenced by The Graduate (1967). Both films feature The Smiths' song "Please Please Please Let Me Get What I Want." Both leads have a Greek chorus represented by one interesting and one disappointing friend, a brunette and a blonde. And both protagonists try to connect with a girl whose ex-boyfriend Charlie is in a band. This influence makes sense since screenwriter Scott Neustadter is British.
Zooey Deschanel (Summer) has many connections to Simon & Garfunkel; in 500 Days of Summer, she cries while watching The Graduate (1967) with Tom (Joseph Gordon-Levitt). The Graduate's famous music was provided by Simon & Garfunkel. At this point in the film, Simon & Garfunkel's Bookends Theme plays in the background. In Almost Famous (2000), Zooey's character gives her little brother a Simon & Garfunkel album.
According to a video essay by Sloan Stowe that includes the author's videos and an article by the author, this entire film was an act of revenge by Scott Neustadter to smear an ex-girlfriend. Scott wrote the entire film thinking Tom was the hero and Summer the villain, and possibly went so far as to set up a Facebook page for her, supposedly by her, that is still active. Scott never got over his passive-aggressive hatred for his ex-girlfriend.
Matthew Gray Gubler suffered a serious knee injury during filming that required surgery, which was written into his main TV series Criminal Minds to explain his use of crutches at the start of season 5.
When Tom fixes his hair after a night with Summer, a young Han Solo winks at him.
The song being sung at the karaoke bar when Tom enters is "Every Rose Has Its Thorn" by Poison.
This was the third time Joseph Gordon-Levitt played a character named Tom. He had previously played Tommy Solomon in 3rd Rock from the Sun (1996). And Tommy Burgess in Stop-Loss (2008).
A copy of Paul Cezanne's famous "Blue Vase," an important part of Cezanne's influence on Cubism, is in Summer's apartment.
In the parody scenes, Tom meets a mime. Several years later, Joseph Gordon-Levitt would play a mime in The Walk (2015).
The Black Jack whiskey bottle is the same as Jack Daniels but has a different label.
Patricia Belcher has a recurring role in Bones (2005), which stars Zooey Deschanel's sister Emily Deschanel.
Several members of the film's cast and crew would later appear in superhero projects. Director Marc Webb would go on to direct two Spider-Man films for Sony: The Amazing Spider-Man (2012) and The Amazing Spider-Man 2 (2014). Joseph Gordon-Levitt would later appear in The Dark Knight Rises (2012), and Clark Gregg would play Agent Phil Coulson in the Marvel Cinematic Universe films Iron Man (2008), Iron Man 2 (2010), Thor (2011), The Avengers (2012), Captain Marvel (2019) and the series Agents of S. H. I. E. L. D. (2013).
Vivian Nixon's debut.
20th Century Fox's Region 1 DVD includes an audio descriptive track.
This was the first film written by Scott Neustadter and Michael H. Weber to feature Marvel movie actor Clark Gregg (Agent Phil Coulson). They later wrote The Spectacular Now (2013), starring Miles Teller (Reed Richards) and Brie Larson (Carol Danvers), and The Disaster Artist (2017), starring James Franco (Harry Osborn).
Three actors in this film worked with the comedy duo BriTANicK (Brian McElhaney and Nick Kocher): Joseph Gordon-Levitt in Re: The Number 2 (2015), Clark Gregg in Much Ado About Nothing (2012) and Minka Kelly in Accidental Text (2019).