Corrected entry: At the end underneath parliament Irene Adler takes two bullets out of a gun to use the gun powder, however, she spent all the bullets shooting at Dredger.
Corrected entry: Since when do you have to travel from 221B Baker Street to Pentonville Prison across the Thames?
Correction: If you're referring to the scene when Holmes and Watson are on their way to see Blackwood before his execution, remember they aren't coming from Baker Street, but rather The Punch Bowl.
Corrected entry: The idea of the cyanide bomb being placed under parliament was that it would kill all the Members of Parliament except those that Lord Blackwood wanted alive (these individuals had been given the antidote to cyanide). In reality, there is no "antidote" to cyanide, therefore the plot is flawed.
Correction: There certainly is an antidote to cyanide. The modern method is to administer hydroxycobalamin, which reacts with cyanide to form cyanocobalamin. Cyanocobalamin can be eliminated by the kidneys. The major mechanism to remove the cyanide from the body is by enzymatic conversion by the mitochondrial enzyme rhodanese to convert cyanate to thiocyanate, which is a relatively non-toxic molecule that is excreted in the urine. (From Wikipedia).
Corrected entry: In the scene where Holmes is defending himself with some sort of electrical prod, it's clear that the tips of the prod have the same electrical potential (they are connected to the same metal). Subsequently, this device could never be used to shock anyone unless they were standing on a metal plate that was connected to the opposite electrical pole of the prod tips. If it had a Leiden-Jar type power source, it would have been expended after the first jolt.
Correction: Actually, the rod wouldn't need positive and negative prongs on the same end. The negative terminal is on the opposite end of the rod. When Holmes is charging the capacitor, it rests in a cradle that makes negative contact on one end and positive on the other. So, fully charged, you would want to point the positive end toward your target; as long as that target was grounded, the capacitor would discharge through the target.
Corrected entry: It is 3 miles from the Houses of Parliament to Tower Bridge, so not the quick jog along a sewer pipe that the film would have you believe for the climax of the movie.
Correction: Compressing events, such as a three-mile run, for the sake of the film's pace/running time is a common and understandable movie convention.
Correction: She spent all the bullets in her gun. However, she picks up the gun previously kicked out of Holmes' hand and uses the bullets out of that gun to dismantle Blackwood's weapon.
bookworm1973