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)mphe
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.Bruce Trestrail
Continuity mistake: In the scene where Watson is moving his things out of the room and Holmes is examining a body, Holmes walks and goes to get a book once he returns, and Watson says "it will probably be a factory by the river" when the camera cuts back to Holmes one side of his shirt collar is down, although both sides were popped just seconds before, and seconds later the collar goes back to being popped. (01:16:45)moveaddict
Character mistake: Near the start, Sherlock reads a newspaper dated Friday November 13th 1890 - that day was actually a Thursday. About an hour later he reads another newspaper dated Friday November 19th 1891. If a week had gone by it should have read the 20th - a year could have gone by, but that date was again a Thursday.digger
Continuity mistake: In the scene where Holmes is jumping from the office in the Houses of Parliament, the camera shot from the inside of the office as he jumps out of the window shows that his body is not fully out of the window as he falls down (his legs are still in the room). However, the view outside of Parliament shows Holmes jump clear of the window before he descends to the river. (01:38:45)rob694
Revealing mistake: In the scene where Holmes is sitting on the chair next to Sir Thomas's dead body, the body's eyelids twitch.
Continuity mistake: At the end of the film, in the bridge confrontation between Holmes, Blackwood and Irene Adler, Lord Blackwood forces Adler to the edge of a precipitous (and deadly) fall into the Thames. There is even a perspective shot, looking straight down, of her heels teetering on the edge and nothing between her and the river except two sailboats far below. There are obviously no scaffolds or other means of obstructing her fall in this shot. It's a dead drop. Then Blackwood shoves her straight backwards over the edge. But, when Holmes looks over moments later, Irene Adler is safe and sound on a convenient bit of scaffolding that magically appeared just a few feet below.Charles Austin Miller
Plot hole: After the scene at the Houses of Parliament where Irene Adler escapes through the sewer from the clutches of Lord Blackwood, she suddenly appears at Tower Bridge, about 3 miles away. Even assuming she ran there and the journey was skipped, going there makes zero sense. It slows her down, leaves her exposed and limits her exit points - she's got all of London to escape into! (01:48:00)