From: ep. 2.2, 1.3
Reference From 1.3: Sherlock hands the sneaker–sorry, trainer— to John, asking him to use his methods and tell him what he sees. John sees a couple things, for which Sherlock first compliments him and then tells him he’s “missed everything of importance” (a line from “A Case of Identity, btw). This echoes the very beginning of “Blue Carbuncle” when Watson comes in to find Holmes in contemplation of an old bowler hat, which he then extends to Watson to test his skills.
Reference From 2.2: Sherlock notices a betting sheet in Fletcher’s pocket, and so starts a conversation including a fake bet with Watson in order to get information from an otherwise reluctant source. This happens in “Blue Carbuncle” with the goose-seller, and it’s a delightfully humorous scene, performed especially well by the Jeremy Brett Holmes and ensemble (I have embedded the entire episode below for your viewing pleasure).