The man behind the desk looks at the contract about the time safari and the two engage in small talk.
The man behind the desk explains the rules about the trip, what to do and not to do, to listen to the guide and to never step off the Path.
The guide tells him that if you do one mistake you can jeopardize the future.
The guide timed everything right for the appearance that the hunter's prey would come, when it appeared the man got nervous and froze up. The man accidentally stepped off of the Path and the guide was mad and told him to go wait for them at the time machine.
The tree branch fell on the dinosaur as it should have to end its life and everybody went to the time machine to go back to the future. The guide was very angry and told him they wouldn't go back to the future until he cleaned up his mess when he did they returned to the future.
When they returned to the future it wasn't the same as they had left it. The guy who stepped off the Path changed the outcome of the future from killing a butterfly so the safari guide shot and killed him.