Revealing mistake: When Roy and Chon arrives in London you can see ships on the river Thames. However the sails on the ship are to tall for the ships to be able to get under the bridges. (00:21:45)
Other mistake: During the fight in the outdoor market, while Jackie Chan is trying to use a wooden box to defend himself from a villain, notice that the knife the villain uses bends like rubber as it hits the box. (00:30:00)
Revealing mistake: During the "Singing in the Rain" segment of the big fight after Chon and Roy arrive in London, watch carefully when Chon "lifts" himself with one arm, raising his legs to the side to dodge a strike. It's clear that wires were used, as his body somewhat unnaturally lifts up. (00:31:15)
Continuity mistake: In the library fight scene, Chon (Jackie Chan) is on the ladder and kicks the books on one of the shelves and the shelves collapse. But in the next shot, all the books are gone whereas they should still be there. (00:50:20)
Continuity mistake: If you look closely during the fight scene in the library, the guy that Jackie Chan traps in the ladder is not the same person from the moment he gets trapped to the moment he gets knocked out. (00:50:45)
Factual error: In the scene after Chan and Wilson crash their car into Stonehenge they walk away and the view is of a field and a beautiful blue sky. In the sky you can see an airplane vapour trail up on the left hand side of the screen. There were no airliners in 1890. (00:58:50)
Continuity mistake: When Chon and Roy are talking in the bar, Roy has a shot and puts the glass on the table with other glasses. A few shots later the glasses has changed positions. (01:04:25)
Continuity mistake: Lin's ankles are shown tied with neat loops of ropes and no link between them. A couple of shots later her ankles are sloppily tied and tied together. (01:12:38 - 01:13:26)
Factual error: In the scene where the English police come to Madame Tussaud's Wax Museum, they are waving flashlights, which are seen when they exit the museum. The film is set in 1887; the flashlight wasn't invented until 1898 (according to About.com). (01:19:45)
Continuity mistake: During the climatic fight scene between Jackie and the baddie in the Clock Tower, the background was the inner side of the clock. There was silhouette of the clock's hand without Owen on it when Jackie was dueling the villain on the platform. However, when Jackie and the villain crashed through the same clock face, Owen was hanging on the clock's hand. (01:33:30)
Factual error: The first Kinetoscope (arcade of 'personal movie viewers') was opened in 1894 and the first motion picture studio was located in New Jersey. There is no way that they would have known enough about motion pictures in 1887 to go into them, let alone go to Hollywood to do so. And the use of the word 'movie' is at least twenty years too early.
Factual error: Everyone is abuzz about Jack The Ripper. The setting, however, is around the time of the Queen's Jubilee, which was 20-21 June 1887. Jack The Ripper did not become known to the public until September 1888.
Continuity mistake: In the final sword fight between Rathbone and Jackie, you can see Rathbone's swords flex along the edge more like rubber than a steel sword.
Continuity mistake: When Roy and John are talking about getting Lin out of prison, there is a shot of her looking definitely to her right, the shot then goes behind her and we see that both Roy and John are on her left.
Factual error: The young pickpocket is revealed at the end to be the actor Charlie Chaplin as a child. The film takes place around the time of the Queen's Jubilee in June of 1887. Charlie Chaplin wasn't born until April 16th 1889.
Continuity mistake: In the market place fight scene, Jackie Chan uses an umbrella to defend himself. In one shot, he breaks the umbrella edge, bending it out of shape. In the next shot, it looks brand new.
Factual error: Several real-life events are off in the movie's timeline. The movie itself is set in 1887, yet it includes Arthur Conan Doyle beginning writing Sherlock Holmes, although he did so before 1887; a mention of the Savoy Hotel, which was not built until 1889; and many references to and an appearance from Jack the Ripper, who was not active until 1888.
Continuity mistake: During the fight with the street gang, Jackie Chan is about to jump onto the cloth roof to send a gang member flying away. Watch the first half of the shot (from behind Chan) and the cloth in the section Chan is about to jump into is hanging down in the space between the joists and is very slack. When the shot changes from the front to show Chan jumping and landing into the cloth, the cloth is now stretched tight for his landing.
Continuity mistake: The position of Jackie Chan's sword in the gears of Big-Ben changes between the shots we see. It goes from being almost fully in, to about half in.
Continuity mistake: During the library and museum scenes particularly, the heights of candles and the amount of light given off by them varies significantly from shot to shot. This is because Jackie Chan fight scenes tend to be filmed over a matter of weeks.
Answer: It is never really mentioned, but we can assume it is the home of some noble or "higher class" person, from all of the elaborate things.