There are a number of literary elements present in this classic play by Arthur Miller. In addition to the two kinds of irony stated in the earlier response, one very obvious literary element is that of allegory. Miller wrote the play intentionally to comment upon the McCarthy hearings, which were referred to as a "witch hunt" at the time.
This is an interesting point, since there were some who referred to the hearings before the United States Senate's Subcommittee on Investigations as a "witch hunt"; and yet, for the most part, it was McCarthy's investigation into the "Un-American activities" of various citizens that was the larger problem. This demonstrates the way that the term "witch hunt" can be manipulated to mean both the persecutor and the persecuted.
In 1954, McCarthy was accusing citizens of Communist sympathizing and spying with little evidence and through hearsay; in much the same way, people in Salem Village are accused of witchcraft with only "spectral" evidence, plus rumor and hearsay. These parallels indicate what a perfect allegorical framework exists in The Crucible for pointing out the hypocrisy and predatory behavior of the accusers in McCarthy's day, as well.
In addition to allegory, an additional literary element is that of metaphor, present in the play's title. A "crucible" is a container used for heating materials to a very high temperature such as metals or glass. Similar to a witch's cauldron, the crucible is meant to melt down matter to form something else. The word also means "a severe test," and surely these events were tests of the durability of truth, compassion and justice, both in 1692 and 1954. Merriam Webster offers a third definition: "a place or situation in which concentrated forces interact to cause or influence change or development," which is also very applicable to both situations.