Although Christopher Nolan has said in his comments on the film's ambiguous ending that he believes Cobb is reunited with his children, he leaves the question of whether the top keeps spinning to the viewer's interpretation. For the director, what really matters is that Cobb is no longer obsessed with his dreams.
In an interview with Entertainment Weekly, Nolan likens the Inception team to the hierarchy of a film set: Cobb represents the director, Arthur the producer, Ariadne the production designer, Eames the actor, Saito the studio and Fischer the audience. It is a reflection of Nolan's own creative process.
Cobb's wedding ring is never visible outside the dream sequences. The camera deliberately changes angle at the moments when the character's left hand would enter the frame, keeping this detail hidden.
The solution diagram Ariadne draws is a direct reference to King Minos's Labyrinth. The character's name also alludes to Minos's daughter in mythology; the Ariadne of the film likewise takes on the role of the architect who enables the team to find its way through the dream labyrinths.
The fifty years Cobb and Mal spend in limbo correspond to roughly ten to eleven hours of sleep in the real world when the time dilation between dreams is calculated. Saito's aging in limbo over the course of the flight confirms this mathematical consistency.
The phrase "The Alternate State" on the vehicle license plates in the first dream level entered with Fischer is a subtle clue about the perception of reality.
The name Dom Cobb is a nod to the architect Henry N. Cobb, known for his skyscraper designs. The fact that the world the character builds in limbo consists largely of skyscrapers reinforces this connection.
The initials of the main characters' names (Dom, Robert, Eames, Arthur, Mal, Saito) come together to form the word "Dreams." When Peter, Ariadne and Yusuf are added, the resulting phrase "Dreams Pay" becomes a professional description of the mind thieves.
The "don't think of elephants" metaphor Arthur uses while planting an idea in Saito's mind is a salute to George Lakoff's book on conceptual framing, "Don't Think of an Elephant."
The running time of 2 days 9 hours 14 minutes that appears in the film's cable listings is the time spent in the dream world converted to real life.
Édith Piaf's song "Non, je ne regrette rien" is woven into the fabric of the film through its themes of memory and regret. The line "Ni le bien qu'on m'a fait ni le mal" is a pun on Cobb's wife, Mal.
The Penrose stairs Arthur shows Ariadne are a reference to M.C. Escher's "Ascending and Descending," a work built on optical illusions.
Michael Caine settled the debate over whether the film's ending is real or a dream: Nolan told him, "The scenes you're in are real, the ones you're not in are dreams"; since Caine appears in the final scene, the events are real.
The film cuts a total of 223 times between the dream levels and the story's timeline.
The film's running time of 2 hours 28 minutes is a tribute to the 2 minutes 28 seconds of Édith Piaf's original recording of "Non, je ne regrette rien."
The name Dom means "home" in the Slavic languages and derives from the Latin root "Domus," which is directly connected to Cobb's desire to return home.
The name Yusuf is a reference to the Prophet Joseph, known in the Bible and the Quran for his ability to interpret dreams; the Yusuf of the film is likewise the one who controls the dream chemistry.
The hatred Cobb voices as he gets off the train is a tragic premonition of Mal's line "You're waiting for a train" and of their deaths beneath the train in limbo.
The children's line at the end, "we're building a house on a cliff," is a direct reference to Saito's house at the edge of a cliff at the beginning of the film.
The name Robert Fischer is a tribute to the chess legend Bobby Fischer, while his father Maurice Fischer is a tribute to the master of optical illusions M.C. Escher (Maurits Cornelis Escher).
The number 528491, scattered throughout the film from hotel rooms to safe combinations, is not merely a coincidence but a mathematical prime number.
The appearance of Cobb's left hand in the scene where he holds out his passport at customs is one of the most concrete clues the director leaves the viewer about the fate of the top in the finale.
The name Ariadne represents the thread that allows Theseus to escape the labyrinth in mythology; in the film too, the character is a guide who shows the team the way through the complex architecture of the dream levels.
The only moment the character played by Tom Berenger appears in the real world is in Maurice Fischer's office; his presence in all other scenes is nothing more than a projection of Fischer's mind.
The character Eames sends a direct greeting to the couple Charles and Ray Eames, who revolutionized furniture design and architecture.
The name Mal is derived from the French word "malheur," meaning "unhappiness"; it is a pun that sums up the character's destructive and toxic effect on Cobb.
Despite the intense action in the film, only two characters die in the real world: Maurice Fischer and Mal. All other losses occur within the fictional boundaries of the dream levels.
The film's logo in the form of a labyrinth bears a striking resemblance to the visual identity of Christopher Nolan's production company, Syncopy.
Inception has gone beyond its dictionary meaning to become a new term in popular culture describing the process of planting an idea in the mind.
The extradition dialogue in Cobb and Miles's first meeting is a reference to DiCaprio's 2002 film "Catch Me If You Can"; in both films the character is arrested in France and extradited to the United States.
The painting in Saito's mansion is Francis Bacon's 'Study for Head of George Dyer'. With this choice, Nolan both references art history and reinforces the character's state of mind through Bacon's dark aesthetic.
The number sequences in the film were not chosen at random; the figures 3502 on the front of the train and 2053 on the taxi's number plate serve as a kind of signature for attentive viewers.
A total of 399 questions are asked over the course of the film. Of these, 113 belong to Cobb, 93 to Ariadne and 44 to Arthur; this distribution also lays bare the characters' prominence in the story.
Francis Bacon, whom Nolan and Heath Ledger drew on for the Joker's design in 'The Dark Knight', also appears in the painting Mal examines in Saito's dream.
The team has a global makeup, with characters drawn from five different continents: Cobb, Arthur and Mal from North America; Ariadne from Europe; Eames and Yusuf from Africa; Saito from Asia and Fischer from Australia.
The mirrored scenes on the Paris bridge that create the Droste effect are a visual signature nodding to Nolan's 'Memento' and 'Doodlebug'.
The EP cover designs for Zack Hemsey's track 'Mind Heist' refer directly to the tragic scene in which Cobb and Mal lie on the tracks and to the tension created by the approaching train.
The name 'Cobol' in Cobol Engineering, the company Cobb works for, is a nod to 'Common Business Oriented Language', the programming language used for data processing in the business world.
The unsettling tones felt in Hans Zimmer's compositions show a striking parallel with Bernard Herrmann's 'Vertigo' theme; both films share the dreamlike atmosphere of an obsessive love.
Most of the team members, Saito included, are referred to only by their first names throughout the film; the only exceptions to this rule are Robert Fischer and Eames.
Earl Cameron, who plays the old man, was etched in memory for his role as an administrator in the cult mind-control and dream-themed series The Prisoner; this connection to Inception's atmosphere is surely no coincidence.
The film's iconic line 'You're waiting for a train...' appears as a vocal sample at 3 minutes 28 seconds into nExow's track 'Far Away'.
The Edith Piaf classic 'Non, Je ne Regrette Rien', used as the wake-up signal, also echoes at the close of Bernardo Bertolucci's The Dreamers.
Michael Caine, who brings Maurice Fischer, Robert Fischer's father, to life, was really named Maurice Micklewhite; with this subtle detail Nolan builds a hidden bridge between character and actor.
The name Cobb is not a first for Nolan; the director had also given his lead character the same name in Following, his 1998 debut feature.
'Bar Valfierno' in the second dream level takes its name from Eduardo de Valfierno, the con man who allegedly stole the Mona Lisa in 1911 but whose existence is historically disputed.