During one of the earlier scenes while Maurice and others are reading/translating with a professor/dean, Maurice is seen clearly wearing a wristwatch. While wristwatches did exist at the time they were rare, and were considered working class so would not have been worn by a gentleman. The wristwatch would not become common until the first world war, when they were given to soldiers to allow them to see the time while both hands were engaged.
Wigmore Hall, where the boys meet in one scene, was known as Bechstein Hall until 1917. It was owned and operated by the German piano manufacturer Carl Bechstein & Sons. In1916 Britain seized German property in Britain. The hall was renamed Wigmore Hall on its reopening in 1917. So "Wigmore Hall" did not exist when the scene in the film (pre-war) takes place.
Maurice Hall and Clive Durham are shown attending a concert at the Wigmore Hall in London in 1911. This renowned concert venue was originally called Bechstein Hall, having been built by the famous German piano firm, and was not renamed Wigmore Hall until after the First World War, when anti-German feeling had caused the owners to sell up and Westminster Council renamed the venue.