The tone of "A Sound of Thunder" is suspenseful and critical, as the story uses a science fiction narrative about time travel to warn readers about the dangers of technology and comment on the apprehension of authoritarianism. The use of foreshadowing builds anticipation and carries the story to its ironic ending. By outlining the consequences that one man can cause using the Time Machine, the story demonstrates how technological advancements can harm society, particularly when gone unregulated or unsupervised.
The story also has an arrogant tone, particularly in the moments where Eckels becomes the narrative driver. After all, the plot revolves around Eckels's desire to hunt down a Tyrannosaurus, one of the most formidable creatures of all time, simply for sport. Eckels believes that he is brave enough to kill the Monster and is confident enough to pay $10,000 upfront. However, his confidence quickly devolves into cowardice, causing the hunt to go awry:
"I didn’t realize it would be this big,” said Eckels. “I miscalculated, that’s all. And now I want out."
Eckels's decision to back out of the hunt endangers the entire group and causes unnecessary chaos. Accordingly, Eckels's overconfidence becomes the catalyst for both the falling action and catastrophic ending of the story.