Eckles is giving his check for $10,000 and agreeing to the terms of time traveling, if he messes something up he could be fined and government action could be taken
Travis explains to Eckles in the time machines why its important he stay on the path and not touch anything, if anything in the past is disturbed it could alter the future and be catastrophic. Travis also tells them that they only kill things that were going to die anyways
The group encounters the dinosaur they are looking for , but Eckles becomes scared and runs off the path. The dinosaur sees them and the group shoots it down .
Eckles ran back to the time machine and was found by the rest of the group sniffling by himself, Travis is angry with Eckles and tells him to get out and retreive the bullets from the dinosaur with a knife or else he will be left there forever.
after Eckles retrieves the bullets from the dinosaur the group returns to the present and notices that things are different. Eckles looks at his shoe and realizes he stepped on a butterfly and killed it, changing the future.
Travis is so angry with Eckles that he shoots kills and him for changing the future .