Trivia: When Frank Castle is in the jail cell, he has nightmares and flashbacks to his family before and during their execution at the hands of the mafia. In one of the shots, his daughters can be seen wearing Spider-Man pajamas when squirting water guns at him. This is a homage to the Punisher's very first appearance in 1979's comic, The Amazing Spider-Man #129, in spite of the director's desire to distance the movie from the comics as much as possible.





Answer: With how many criminals Frank has killed, many of them would definitely want revenge. By hiding in the sewers, there's less chance of him or his hideout being discovered. If Frank lived anywhere above ground, his enemies would be able to find him more quickly and kill him.