Factual error: The film features characters going through 3 doors in the Temple which are always locked. The first is the one Sophie and Robert leave the church by, the second is the one they leave Temple itself by and run onto Fleet Street - this one is shut in the film, but it's always locked in that case. Finally, the car leaves Temple onto Fleet Street using a door that is always, always locked.
Factual error: The temple church is very light, bright, and airy - especially on a sunny day like it was in the movie, it would have been very bright on the inside, not dark and dreary at all.
Factual error: When Teabing is almost arrested by British police at Biggin Hill, all the police are armed. Throughout all the shots, however, the windshields of the police cars are blank. All cars that carry armed police have three yellow dots on the windshield.
Factual error: People who've actually been to Rosslyn (the correct spelling, though it is in the village of Roslin) Chapel will be amused to see in the movie that Tom Hanks and Audrey Tautou were somehow able to bypass the many security guards, the gift shop, tea room, museum and admissions desk to get into Rosslyn, and also that they did so via a door that is always locked beyond two stout gates. No one ever enters Rosslyn the way they did.
Factual error: "Madonna of the Rocks" hangs in the Grand Gallery, not the Salle des Etats. The painting directly across from the "Mona Lisa" is Caliari's "The Wedding Feast at Cana." This painting is an enormous 32 feet (9.9 meters) wide. Even if "Virgin of the Rocks" did hang opposite the "Mona Lisa," it's 6.5 feet (1.99 meters) tall, too tall for Sophie to see over. The painting's ornate wooden frame is also too heavy for an average person to lift unassisted.