When Michael referred to Conan Doyle Nigel corrected him, saying "It's SIR Conan Doyle!". This is incorrect. Knights and baronets are never referred to as Sir Surname; they may be referred to as Surname or as Sir Forename Surname, so in this case Conan Doyle is correct, as would have been Sir Arthur Conan Doyle. Perhaps the director was unaware that Conan Doyle is a double-barrelled unhyphenated surname.
The character of Nikita speaks fluent Russian. However, when she tells Michael that Tupelov is at the "Tovarish Cafe", she mispronounces the name as "TOH-va-rish." The word means "comrade" in Russian and is pronounced "ta-VAH-rishch." Since Nikita is fluent in Russian, she should have known this.