"When they searched my car, they said that they found a gasoline canister and I think duct tape. Who wouldn't have a gasoline canister on them when driving 3,000 miles across country?"

Sherman Austin's quote is a sarcastic reaction to the cops's allegation that he was planning to dedicate a criminal activity. He is indicating that it is typical to have a gasoline canister and duct tape when driving 3,000 miles across country. He is indicating that the authorities are overreacting and that he is innocent. He is likewise indicating that the police are being unreasonable which they are searching for something to incriminate him with. Austin's quote is a method of expressing his disappointment with the authorities's actions and his disbelief that they would accuse him of a criminal activity based upon such insignificant items. It is also a way of highlighting the oppression of the scenario and the unfairness of the authorities's actions.