The opening paragraphs of Bradbury's short story give a good sampling of the kinds of literary devices that are represented in "A Sound of Thunder." He opens right at the start with sensory imagery, which uses language evoking images of sights, sounds, feelings, textures (touch) and smells. In the first line, the protagonist swallows and we are told about the "muscles around his mouth" and he waves a hand, while in the background is a "sound like a gigantic bonfire." A few lines later, there is also "A touch of a hand."
The opening paragraphs also present the literary devices of flashback and foreshadowing. These are time manipulation devices that allow the author to weave in and out of past present and future at will to fulfill her/is intentions for plot and story structure. The opening lines also show that metaphor is represented in Bradbury's story. A metaphor compares unlike things. Bradbury compares death to three very unlikely things: freshness, seeds and greeness: "fresh death, the seed death, the green death."
Flashbacks step back to a time preceding the present moment in the narrative. In the present time within the context of "A Sound of Thunder," the protagonist is at a time travel agency booking passage on a safari. While there, he recollects an earlier time. This recollection of the past provides a flashback to previous events. Specifically, in this flashback he tells about the company's advertisement and, in so doing, provides background information about time travel, the time travel company and his own interest and motivation.
Foreshadowing works two ways. The first, often used in short stories, is the provision of subtle hints about what is to come so that the surprise endings of short stories are not unprepared shocks. The second is the provision of what may or will happen in the future. It is this second type that Bradbury employs in "A Sound of Thunder."
The safari sales agent tells the protagonist directly that if he violates any instructions, he will face "possible government action" upon his return. This use of foreshadowing does two things. First, it indirectly tells what kind of world the protagonist lives in (e.g., "government action"). Second, it opens the readers eyes to what kind of adventure he is going on, which also sheds light on his character traits and motivations.