Hugh Jackman took etiquette lessons from 19th-century etiquette expert Jane Gibson (who trained actors for such projects as Sense and Sensibility (1995)). He also studied ballroom dancing and trained to ride a horse for the film.
According to the DVD commentary, several of the film's actual crew members appear in the crew of the margarine commercial.
When Meg Ryan knew that Hugh Jackman was going to spend his wedding anniversary alone, she phoned his wife to invite her to dinner. Reportedly, Jackman had to spend the day working.
There are 2 different versions of this movie available on the DVD menu. One is the theatrical version which runs for 113 minutes where the other one is a directors cut which is 7 minutes longer than the original version.
The only differences between the two is Kate can be seen in 1876 at the very beginning as well as a surprise cameo by James Mangold at a movie conference. There is also the implication that Kate is a distant relation to Stuart.
When Leopold is chasing Stuart down the stairs and out of his house, Stuart seems to jump a few meters in a second. In the "Director's Cut" version, the two guys actually bump into Kate there.
James Mangold: the film director arguing with Kate about the likability of the leading lady in the film the focus group has just been watching.