When Watson first meets Nathan Garrideb, the professor is holding a specimen of a bat, which he refers to by a binomial name, the first part of which is "Vespa". Vespa is, in truth, the Genus of all 'True' Hornets, which are members of the Order Hymenoptera, of the Class Insecta. Bats belong to the Order Chiroptera, of the Class Mammalia.
James Villiers (Lord Cantlemere) is correctly listed in the end credits, but in the opening credits he is incorrectly listed as "James Villers".
The revolver Mycroft gives Watson is once more a Webley Mk VI, first made in 1915, well after the story is set.