Other than Watson, Mrs. Watson, Lestrade and Mycroft. Of course there is Wiggins (forget which of the boys is him) and the other street urchins who made up the Baker Street Irregulars. Is there anyone else in the church we are meant to recognize as a past colleague, client or rival? I don’t see anyone with bright red hair who might have been Mr. Jabez Wilson, for instance.
Mrs. Hudson is sitting between Mary Watson and the gnome-looking guy, and Clarkie, the only constable Sherlock seems to have any respect towards, is sitting next to Lestrade.
If you jump to the 35 second mark, I think the guy wearing a tie, with a kid in front of him, is the guy from the prison yard in the first movie, who Sherlock tells a dirty joke to.