The hand that is seen with the BB lodged between its knuckles is not Ben Stiller's, but Andrew Wilson's, brother of Owen Wilson and Luke Wilson. When they were children, Owen fired a BB gun at Andrew's hand and the pellet has been there ever since.
The original hawk used to play Mordecai was kidnapped during shooting and held for ransom - production could not wait for him to be returned which is the reason that the bird that appears later in the movie has "more white feathers" - it's a different bird.
The brand of cigarettes Margot smokes throughout the movie were only sold in Ireland and were discontinued in the 1970s. According to director Wes Anderson in the DVD insert (detailing all of the setting and props and the reasons why he used them) this was intentional, both because of the theme of the 1970s and to make Margot's secret smoking habit just a little stranger.
Jackson Browne, who wrote and played guitar on the song "These Days" used in the film, forgot he had given permission for the song to be used until he saw the film. He described this in an interview, "I forgot that I'd licensed them to use this song. And this is one of those things that comes to you in the mail and you don't know what they're talking about and you simply give them their permission. You're sitting in the movie theater and there's this great moment when Gwyneth Paltrow is coming out of a bus or something like that. I'm thinking to myself, I used to play the guitar just like that. And then the voice comes on and it's Nico singing "These Days", which I played on."
The scene where Richie punches the glass in Mordecai's pen is unscripted, this was improvised by Luke Wilson on the spot and the scene quickly cuts to Richie and Ralleigh (Bill Murray) talking up close, this is because when Wilson punched the glass, director Wes Anderson thought he seriously hurt himself.
Gene Hackman mentioned in interviews that he was somewhat hesitant to accept the part, as he felt that he himself had been insensitive to his own family at different points in his life. He asked them if they would find him playing this character uncomfortable for their own sake. They all agreed he should accept the part.
Brian Tenenbaum, who plays one of the paramedics, was a college friend of Wes Anderson and brothers Owen Wilson and Luke Wilson at the University of Texas. His name was used for the film and family because, says Anderson, "I just like the name." Brian Tenenbaum's sister is named Margot.
Etheline Tennenbaum's character is loosely based on director Wes Anderson's own mother Ann Buroughs who, after divorcing his father, became an archaeologist. Burroughs' actual glasses are worn by Etheline.
Wes Anderson and Andrew Wilson provided the voices for the commentators during Richie Tenenbaum's tennis match. Many viewers thought it was a cameo from Jason Schwartzman, star of Anderson's previous film, Rushmore (1998). Also, the Wilson brothers all have similar sounding voices, therefore many people think that it is Owen Wilson providing the voice of the second commentator. Anderson also plays bass on the reggae in the initial sequence.
Although the exteriors were largely shot in New York, Wes Anderson intentionally avoided virtually all shots of skyscrapers or other distinctive New York landmarks. In one scene, Royal and Pagoda are talking in Battery Park (on the southern tip of Manhattan) and Anderson intentionally had Kumar Pallana (Pagoda) stand directly in front of the Statue of Liberty so it wouldn't show up in the shot.
The movie is set in a fictionalized version of Manhattan, with such imaginary addresses as "100 N. 30th Avenue" (the address of the hotel where Royal stays) or the "375th Street Y," itself inspired by NYC-area facilities operated by the Young Men's Hebrew Association.
Although "Archer Avenue" is fictional, the "Tenenbaum house" did exist as a practical location at 144th street and Convent Avenue in the Hamilton Heights section of Harlem, in Manhattan. For the film shoot, the production designers rented and completely redecorated the house. The scenes in the kitchen, however, were actually shot in another real house, next door.
Owen and Luke Wilson's mother, Laura Wilson, worked closely with photographer Richard Avedon. Laura documented Avedon's "In the American West" series project. The photo clipping of Owen Wilsons character, sent to Anjelica Huston's character, copies a famous portrait from the Avedon series, of a young man holding a disemboweled snake. The Wilson brothers would definitely be aware of their mother's project, and this would be somewhat of an inside family joke.
Wes Anderson often uses songs from The Rolling Stones in his films. The '"Between the Buttons" album released in 1967 can be seen in young Margot's hands and years later when Margot and Richie talk inside Richie's tent (when the songs "She Smiled Sweetly" and "Ruby Tuesday" from the album play).
After Margot tells Richie that Eli has told her of Richie's letter to Eli that he dictated whilst on the Cote D'Ivoire ship in which he confesses his love for Margot, Richie goes to Eli's house to confront him. Having knocked on Eli's door, the sound of a bird is heard and Richie looks up to see if he can see the bird, it is implied that the bird that made the noise is Richie's recently released bird Mordecai, who comes back to Richie later on in the film
When Bill Murray asks for a cigarette, says "au revoir" (goodbye) and leaves by the end of the movie, it mirrors (smoking aside) the concession speech of French president Valéry Giscard d'Estaing, when he lost the 1981 French presidential election.
The monster-masked men paintings in Eli's apartment are attributed to Mexican artist Miguel Calderón and were part of his 1998 exhibit "Aggressively Mediocre/Mentally Challenged/Fantasy Island (circle one)", though they were not actually painted by him. Calderón took photographs of his friends posed on motorcycles and, after deciding the photographs were not realistic, hired a portrait painter to reproduce them on canvas.
"The Peter Bradley Show," on which both Eli and (it is implied) Margot appear during the course of the movie, is a parody of the long-running interview show "The Charlie Rose Show," which has been produced in the studios of the New York PBS affiliate Thirteen/WNET since 1991 and has been distributed to PBS stations nationwide since 1993.
The ship 'Queen Helena' that Richie travels back home on (seen in the background of the scene at the Royal Arctic Lines terminal where he meets Margot) is really the famous liner Queen Elizabeth 2 (or QE2).
In every Wes Anderson film there is a shot of one or more of the characters underwater. One person is added for each film. In Bottle Rocket (1996), we have one character, Anthony underwater. In Rushmore (1998), we have a shot with two characters underwater. Then in The Royal Tenenbaums (2001), there are three people underwater. The Royal Tenenbaums also stresses the number three. When the on screen novel reads, "3", it cuts to Ritchie, and the narrator says, that Ritichie had fed his bird 3 sardines. Then next we see Ritichie on the roof reading "3 Plays".
The trivia items below may give away important plot points.
Throughout the movie everyone wears the same clothing (or some variation of the same clothing). All of the clothing is also from the 1970s. For example, Richie wears a Fila tennis shirt and headband made famous by Bjorn Borg ca. 1976. Director Wes Anderson did this intentionally so that it would appear that the Tenenbaums are trapped in the era of their heyday while time moves on (the gravestone at the end reads 2001). Much of the setting, including the use of gypsy cabs and Green Line buses, are also in keeping with this theme.
In the bathroom scene where Richie cuts his hair and, eventually, his wrists, the music playing is "Needle in the Hay" by Elliott Smith. On October 21, 2003, Elliott Smith (allegedly) committed suicide through self-inflicted stab wounds. Owen Wilson (co-writer with Wes Anderson) reportedly attempted suicide in 2007. Owen is the brother of Luke Wilson, who played Richie.