In the excerpt, the speaker uses a type of repetition, which is a rhetorical device that repeats the same words or phrases a few time; there are many types and in this case, the repetition is used as an onomatopoeia, a device that recreates the sound of an animal or an object, in this case, it reinforces the idea of movement through the s and sh.
The author is applying imagery by using SHrill, ruSHing, Steam whiStle, it is referring to the sound and image of a train, and the Steam whiStle is to imply that of the steam rising from the train. now the r in RuSHing is to signify the speed or power of the locomotive.
It is a farse because there is all of these funny things going on but at the same time there are other things that make it serious. Also the play, A Midsummer night's dream is a comedy, so it would be comic relief
