The lavender fields are clearly Lavendula intermedia, natural hybrid of Lavendula angustifolia (the true lavender used in perfumery) and Lavendula latifolia. Lavendula intermedia was discovered only at the end of 19th century and cultivated from the 1930's. Its flower is bigger (and the visual aspect more suitable for a movie) than Lavendula angustifolia but its natural essence is less fine.
At one of the very first scenes of Jean-Baptiste execution, right before crowd starts fighting for the best place to see it, an antenna can be seen next to the balcony where the authorities and Laura's father are standing. It is easily identifiable as the peak of Calatrava Telecommunications Tower at Montuich mountain at Barcelona, which is quite near the building where the scene was shot.
Midway through the movie a whore appears with a Pekingese dog. The Pekingese were not formally introduced into Europe until midway through the 19th Century when Britain and France "sacked" the Chinese Empire (circa 1860). The Pekingese were kept exclusively in the Chinese Imperial Palace (Forbidden City) until then and maintained by eunuchs. The movie takes place in the mid 18th Century. While it may be possible British or French royalty could have had a Pekingese (although extremely unlikely), a French harlot owning a Pekingese in the 1700's is an impossibility.
Fifteen minutes into the movie, Jean-Baptiste enters town and sees a carriage with two women inside, one holding a Pomeranian. According to the American Pomeranian Club, "When (Pomeranians) first came to notice in Britain in the middle of the 19th century, some specimens were said to weigh as much as thirty pounds and to resemble the German wolf Spitz in size, coat and color." The film takes place in the mid-seventeen hundreds (the 18th century). The Pomeranian, as we know it today, would not have existed as depicted in the film.
The method of enfleurage that Grenouille is first seen practicing is called cold enfleurage - placing live botanicals in a layer of lard or tallow set in a frame. However, this method of enfleurage was not developed until the 1800's. The movie is set in the mid 1700's.
When Grenouille meets the perfumer, at his house/laboratory, he knows where all the substances are, although he has never been there before. He is able to do this due to his heightened sense of smell, he is able to work out where specific substances are by the scent they give off.