While on production in Rome, Brad Pitt and George Clooney were not allowed back into the hotel because the doorman thought they were vagrants after the actors were caught in a rain storm while jogging.
The Night Fox's mansion is on the shores of Lake Como in Italy. The name of the city overlooking Lake Como is Bellagio. The city and the lake were the inspiration for the design of the Bellagio casino in Las Vegas, site of the heist in Ocean's Eleven (2001).
Before filming began, Brad Pitt put out a memo to all crew members stating that they only address George Clooney as his character's name Danny Ocean or Mr. Ocean. Eventually Clooney found out about this and got back at Pitt by putting bumper stickers on the back of his car that read "I'm gay and I vote" and "Small penis on board."
Matt Damon requested, just prior to the beginning of production, that the script be revised, so that his character would have a smaller role in the story. Damon had just finished shooting The Bourne Supremacy (2004), and claimed that he was too exhausted to play a character that had such a major role in the movie. Director Steven Soderbergh denied Damon's request, claiming that he felt Damon's character was integral to the plot, and that giving Damon less screen time would diminish his character's impact on the plot.
The video camera that Yen uses while in the hotel room is a Canon XL1S. For director Steven Soderbergh's low-budget/star-studded indie film Full Frontal (2002), he used the same camcorder to shoot the film and keep the budget low.
The story of this film was taken from "Honor Among Thieves", a screenplay treatment written by George Nolfi that was originally intended to be a John Woo vehicle. When it was decided that Ocean's Eleven (2001) was going to have a sequel, Warner Bros. asked Nolfi to rewrite the script, adjusting it for the Ocean's Eleven characters.
The white van in which the Fabergé egg is being transported in, is actually from an existing security company, whose name is visible on the side in certain shots (Group 4 Falck). They handle security and emergency services (ambulance and fire brigade) in the UK and Denmark.
The museum intended to be robbed has the name "Galleria D'Arte di Roma" on the outside, but the building is not actually one of the countless museums in Rome (although some exhibitions are held there), but rather the British School at Rome located in the lands of Villa Borghese.
The Americans steal only four out of eight paintings off a wall in the villa of The Night Fox. This is done so the empty frames of the stolen paintings form a shape reminiscent of a hand with outstretched middle finger.
During the sequence in which the audience is re-introduced to the characters, Reuben Tishkoff (Elliott Gould) is getting a tarot card reading. On the table, the card "Five of Wands" out of the Raider Waite deck can be seen. This card mainly symbolizes an upcoming competition between two parts.
The Pulitzer Hotel in Amsterdam played host to the cast and crew for filming. A picture of George Clooney and Julia Roberts can be found on the wall in Pulitzers Bar, and the description beneath mentions that the hotel restaurant was used for lobby scenes.
Europol is located in The Hague, and not in Amsterdam, as suggested in the movie. The scenes at the Europol office with Isabel were not shot in the Europol building, but rather in the city hall of The Hague. The Hague is about 50km south of Amsterdam.
Shooting in the Netherlands caused some train delays. The Thalys that was used in the film accidentally broke the upper contact wire. Since the wire broke at the point where several wires connected, the power on several tracks was lost. It took two hours to undo the damage.
The mark for the first theft in Amsterdam is named Van Der Woude. One of the second unit assistant directors for the film was Basti Van Der Woude. He actually appears briefly in one scene, as the taller of the two suit-wearing gentlemen accompanying Cherry Jones.
The drysuits used by the gang were custom made for the production in two weeks by husband-and-wife team Gareth and Tina Roberts of Gryphon Watersports in Staffordshire, England. Only one of the ten suits ordered had to be fully functioning and waterproof, but the tight deadline still meant that the couple had to work round the clock to get the suits ready in time for the shoot in Amsterdam.
Ellen Barkin, who would play Abigail Sponder in the sequel Ocean's Thirteen (2007), actually shot a small cameo for this film. It was ultimately cut. It can however be seen on the Blu-ray release (under the additional footage section, the "Meet the Team, Again" sequence).
When Bruce Willis is in Tess's hotel room, Linus says to Bruce, "We're looking to come off this pregnancy thing strong. You know, that little statue on the mantle starts smirking at you after a while, know what I'm saying?" Bruce says no, he doesn't. Both Julia Roberts, to whom he refers, and Matt Damon have been awarded Oscars, while Willis has not.
The transportation of the Fabergé Egg is analogous to the real world transport of the Cullinan Diamond in 1905. At 3106 uncut carats, transporting it safely from South Africa to England posed a bit of a problem with regards to security. Detectives from London were placed upon a steamer ship that was rumored to carry the stone, but this was a diversionary tactic. The stone on that ship was a fake, meant to attract those who would be interested in stealing it. The actual diamond was sent to England in a plain box via parcel post.
Linus (Matt Damon) at the museum says to Bruce Willis, "The moment she doesn't talk to you in the restaurant, I knew." He is referring to the movie in which Bruce Willis plays the lead, The Sixth Sense (1999).
Topher Grace mentions to Rusty that he "phoned it in" during a movie with Dennis Quaid. Grace actually did do a movie with Quaid, In Good Company (2004), which was released the same month as Ocean's Twelve.