Prior to shooting the sequence with the car buried in the snow, Brittany Murphy and Ashton Kutcher had an argument, which helped them get through the take without bursting into laughter.
Whilst filming the scene with the cockroach, it went missing and they had to halt filming for twenty minutes while they searched for it.
Ashton Kutcher and Brittany Murphy were romantically involved off-screen whilst the film was being made.
It was an accident: a 10-pound ashtray rebounded off a prop and struck Ashton Kutcher. He recovered, though he had a sizeable lump for about a week.
On first arriving at their French hotel, Tom and Sarah merrily scamper up the stone pathway. The moment was improvised by Ashton Kutcher and Brittany Murphy while filming.
Brittany Murphy did not speak French and therefore had to memorise her French dialogue phonetically.
At the airport, Tom's line — 'Can we get the Le Car for Le Zak?' — was ad-libbed by Ashton Kutcher.
Ashton Kutcher carried out all of his own stunts throughout filming, but a stunt double was engaged for Brittany Murphy.
'I've owned Tonka trucks bigger than this car!' was improvised by Ashton Kutcher.
Christian Kane, who portrays Peter, is the frontman of the band Kane. Their track 'The Chase' is audible in the background at the Caffe American.
Christian Kane and Brittany Murphy had a joint appearance in Summer Catch (2001).
This marked the final acting appearance by George Gaynes prior to his death on 15 February 2016, aged 98.
In a beautiful exterior shot of an Italian piazza, numerous birds are visible, some taking flight as Tom feigns shooing them away. The whole scene was captured naturally, the birds unaware that they were being filmed.
While staying in an Italian hotel, Tom and Sarah lie in bed kissing when a large insect scuttles across Tom's face and neck. He moves around, yet the bug keeps crawling on him. An insect handler placed the cockroach on Ashton Kutcher, and it moved as the actor shifted, making it look as though he was trying to get the creature off. The handler remained off-camera and collected the insect afterwards, while crew members applauded the courageous actor.
Tom's vehicle is a 1970 Dodge Challenger.
The sequence in which Tom and Sarah step into the aircraft lavatory closely mirrors the mile-high club scene in Vegas Vacation (1997).
The yellow car featured in the film is a Tasso Bingo.
As Tom sits reading, Bags brings him a tennis ball and tugs at Tom's trouser leg to indicate he wants to play. Tom relents and throws the ball; it bounces out of an open window and the dog leaps straight out after it. The next cut shows Bags' graveside with his photograph on display. Near the end of the film there is a flashback to the same sequence when Tom tells Sarah what actually happened to Bags. The scene is set in a loft within the flat. The trainers had fitted sheets of Perspex by the balustrade to prevent the dog falling from the loft. One trainer, off camera, tossed a tennis ball near the desk and the dog ran to retrieve it. To achieve the pant-leg pull, a small pouch of cooked meat was taped to the actor's ankle beneath his trousers. The trainer put the dog on its mark and used a hand signal to send the dog to the actor's leg. When the dog scented the meat and the trainer cued "tug", the dog happily obliged. The dog was then given the contents of the pouch when that part of the scene was finished. A special platform was built and secured outside the open window; it was extra wide and padded for the dog's safety and comfort. A trainer stood on the platform to guide the dog as it jumped through the window. The trainers rehearsed the scene several times so the dog was at ease with the action. The trickiest element was getting the tennis ball to bounce out through the window.
In a flashback to how the couple first met, Sarah is shown walking Bags on a lead along the beach while Tom and some of his mates play football. A 10-week-old bulldog pup was used to portray Bags as a puppy. The pup’s real name was Iceman Cometh, and it marked his first appearance on film, although he had been trained to walk on a lead before filming began. The trainer handed the lead to the actress moments before the cameras rolled, and the pup happily walked alongside her.
Brittany Murphy and David Moscow also co-starred in Riding in Cars with Boys (2001).
Sarah's dog, Bags, is a French bulldog called Linus.
Sarah's dog, Bags, displays jealousy by barking as the couple kiss, embrace and topple onto different pieces of furniture. Later, Tom lies on the settee, yet the dog continues to bark at him. When Tom gets up from the settee and begins to leave, the dog, still barking, leaps up onto the settee and takes Tom's place. A trainer positioned the dog on its mark and used a mixture of hand signals and vocal cues to prompt the behaviour. The dog was then rewarded with treats.
The vehicle at which Tom hurls a snowball to attract the driver's attention is a 1966 Mercedes-Benz 200 D (W110).
Andrew Bergman was initially lined up to direct and to rework the screenplay.
Brittany Murphy portrayed a character called Sarah — the same name she used for her role in Sister, Sister (1994).
It is unclear why Sarah's family and Peter call her "Peewee", while Tom is the only one who does not use that nickname.
The deleted scenes make it clear that Tom comes from a mixed religious background — part Lutheran, part Jewish — and that his father is employed in a foundry while his mother used to work as a hairdresser.
