It was actually raining for the filming of the scene where Dex and Emma are holidaying on a French beach. The actors performed under a tarpaulin in their swimsuits.
On location in Scotland, Anne Hathaway exposed her bottom to Jim Sturgess to set the mood for filming the skinny dipping scene. Though doing it in such a position as to avoid being filmed by the crew, she did not anticipate the presence of several cell-phone-wielding residents of the residential complex behind her. Surprisingly, as of August 2011, this footage has not been posted on the Internet, and Hathaway says she is grateful that the residents had the "class" to refrain from doing so.
At 1:18:45, where they were supposed to be in 2003, we see a BMW X6 parked on the side of the road, which in 2007 was a concept model of the BMW company and was later released in 2009.
In July 2003 when Emma enters cafeteria with Jean-Pierre, there's a board next to entrance with prices. All prices are in francs (F). France joined Eurozone monetary union in 1999, so prices should be in Euros.
The Coronas hit, "The Rhythm of the Night", was first released in December in 1993. In the movie it appears in July 1993, 6 months prior to its first actual release.
Emma: A tortilla is either corn or wheat. But a corn tortilla folded and filled is a taco, whereas a filled wheat tortilla is a burrito. Deep fry a burrito, it's a chimichanga. Toast a tortilla, it's a tostada. Roll it, it's an enchilada.