Headscratchers: The Private Life of Sherlock Holmes
Big 'ol Plot Hole - Why the hell wasn't Watson more concerned about being arrested when Holmes insinuated they were gay lovers? This IS set in a time when sodomy was illegal...
In-universe, Watson never got to that point, since Holmes reminded him of all the women would could testify on Watson's behalf. In reality, it's most likely that Billy Wilder simply missed that idea.
There's also no evidence to charge Holmes and Watson with anything of the kind beyond the fact that the two men live together (hardly an uncommon situation then or now) and some gossip. An insinuation isn't proof. Since the ballet is going to be going back to Russia fairly soon Holmes can easily deny he said anything of the kind without anyone to contradict him, and like Watson says once he's calmed down, the two actually aren't in a homosexual relationship, and Watson can provide numerous testimonials to his heterosexuality, so since there's no evidence to suggest otherwise such gossip could be considered slander and pursued through the courts.