When asked why the axe used by his character has the name "OTIS" carved into the handle, Paxton stated that he wanted the axe to have its own personality and to be unique.
He found the name in Pasadena when he was there scouting for locations to film. Paxton met a homeless man and offered to give him some money. The homeless man did not want charity, so Paxton instead offered to buy the use of the man's name for his movie. The homeless man's name was Otis.
Bill Paxton used the same beer can the entire filming of the movie because they could only find one Hamm's beer can like that from 1979. The can was "opened" off-camera and a sound effect added for popping its top (explained in the director commentary at around 52 mins).
At the very end, the two boys that ride scooters across the screen are Matt O'Leary and Jeremy Sumpter, who play Fenton and Adam Meiks as youngsters, "almost like we're in this weird Twilight Zone world." Paxton revealed.
Loosely based on the case of American serial killer Joseph Kallinger who murdered three people and tortured four families. He committed these crimes with his 13-year-old son Michael between 1974-1975 in New Jersey. Kallinger pleaded insanity, claiming God had told him to kill.
The script originally featured a reference to the boys wanting to go see the movie Alien (1979), but Paxton changed it to The Warriors (1979) to avoid the reference to his own work in Aliens (1986).