Factual error: In the scene depicting life on Baker Street (after the "Sherlock Holmes" title), a horse-drawn carriage races through the streets of London. The only problem is, the carriage is driving on the right side of the road with others passing on the left. In England, carriages would be driving on the left. (00:07:05)
Factual error: Holmes and Watson's first encounter with the French giant results in a large steel ship, still under construction, being prematurely launched and then sunk. As it sinks, this ship, which is more than 30 meters long, stands on its bow. There is absolutely nowhere in the River Thames near London where the water is that deep.
Factual error: When Holmes and Watson arrive in Nine Elms you can see Tower Bridge in the background. This wouldn't be possible due to how the river Thames bends, and to the fact that Tower Bridge is several kilometers away from Nine Elms.