What are some elements in "Araby" that are allegorical?
Well, this question is a little difficult to answer as really, this is not an allegorical story in the same way that a story like "Young Goodman Brown" by Nathanial Hawthorne would be an allegorical story. In such allegorical stories, characters, settings and events stand for abstract ideas or moral qualities. If you wanted to push the allegorical reading, you could argue that the narrator represents Romantic innocence, and that by the end of the story, when he experiences his epiphany, he then comes to represent experience as he realises his own foolishness and illusions and how they had dominated his life. Certainly, the key moment of the story is this epiphany, which comes at the end of the tale:
Gazing up into the darkness I saw myself as a creature driven and derided by vanity; and my eyes burned with anguish and anger.
It is at this point that the narrator experiences a moment of self-knowledge, and we know as readers that he will never be the same after this experience.
So, whilst this tale is not normally considered to be an allegory, I think if you really wanted to you could "force" an allegorical interpretation, focussing on the narrator and his transition from innocence to experience.