A Scandal in Belgravia - S2-E1
Corrected entry: It was impossible for Sherlock to guess the password to the safe in Irene's house. Even if he knew which numbers were pressed frequently he couldn't have guessed the order. (00:20:00 - 00:21:00)
The Hounds of Baskerville - S2-E2
Corrected entry: Dr Frankland refers to his "cell number. No British person refers to a mobile phone as a cellphone.
Correction: It's actually a plot point, revealing that Frankland had spent a long time in America.
Correction: Irene waltzing around nude provided Sherlock with all the information he needed: he deduced the password was her vital statistics. Since that figure is most commonly presented in order of bust/waist/hips, the answer would have then come relatively easily to him.
Cubs Fan ★