Continuity mistake: When John Travolta is showing the young boy how to tighten the air filter top, he makes sure the boy gives the wing nut an extra twist. Next he notices a car coming up the road and he leaves. When the FBI agent comes over and looks inside the hood of the truck, the air filter top is again off, the air filter is out and the carburetor is exposed.
Other mistake: After John T's passing, the screen caption reads "1 year later" and they are celebrating his birthday. The light flash happened on his birthday and took three months to be diagnosed and die. The caption should actually say 9 months later.
Trivia: Nate Pope (Forest Whitaker) is an Amateur Radio operator with the call sign WB6QLF. QLF is amateur shorthand for "I am sending with my left foot", a reference to someone whose Morse Code sending skill is very bad. This is normally sent as a question "QLF?" meaning "Are you sending with your left foot?" to an operator who is very difficult to understand in Morse.
Bonnie: George Malley! You learned the Portuguese language in 20 minutes?
George Malley: Not all of it.
Question: Why didn't he use his crazy super intelligence, or his telekinesis, to either find a cure for his tumor or at the very least slide the tumor out of his own brain?