When Greg is examining Denny's (the enthusiast's) body in the coroner's office you can see the giant injury on the left side of his head. But then when Sara and Doc Robbins are looking at pictures from the crime scene the injury is on the right side of his head.
The wannabe Holmes looks out the window of his 221B Baker Street re-creation to see a simulated period London street scene. But the scene shows a ground-floor view; in the Arthur Conan Doyle "canon" Holmes' sitting room was one floor up. This "Holmes" was a stickler for details, so it is unlikely he would have allowed such an obvious error. The wannabe Irene Adler speaks with an English accent. The character of Irene Adler was American, as stated by Holmes in the story she appeared in, "A Scandal in Bohemia".
The wannabes are portraying Sherlock Holmes, Dr. Watson, Irene Adler, and Professor Moriarty. These four characters are obviously meant to reference the old "221B Baker Street" board (and, later, computer) game. However, although Sherlock Holmes, Irene Adler, and Dr. Watson were characters in the game, Professor Moriarty wasn't. The fourth character in the game was the redoubtable Inspector Lestrade. The mistake was undoubtedly due to the fact that Moriarty appears on the cover of the computer game version alongside Irene Adler, Holmes and Watson.