In a subplot of the film, which was cut, Frank Castle finds out that Howard Saint got his information from his friend FBI Agent Jimmy Weeks. He eventually stalks him and drives Weeks to commit suicide. The scene was included in the extended DVD version.
Rebecca Romijn revealed that in a scene where she sews up a knife wound on Thomas Jane, she pushes the needle too far in and ends up actually sewing a couple of stitches on Thomas Jane's body instead of just the prosthetic wound.
The declaration that Frank Castle writes near the end of the film, listing the basis of his vigilante philosophy in numbered order, form the beginning of his war journal, an ongoing diary of his campaign against organized crime. It was the basis for the long-running comic book "The Punisher War Journal".
Jonathan Hensleigh actually knew someone who parked illegally for two years in Manhattan by using the same bogus fire hydrant ploy Frank Castle uses to keep Livia's parking space open during his schemes.
Shooting in Tampa was a double-edged sword. On one hand, the city's downtown area has no residential areas so it would be completely emptied out by the end of the working day - ideal for a film crew. But the city is also prone to lightning storms that roll in suddenly and very violently. The summer that the film crew shot in Tampa was the city's wettest since 1890.
With the supervision of a trainer, Thomas Jane worked out extensively for the role with two hours of weight lifting and cardio, sometimes twice a day and a rigorous diet of health shakes. Jane also trained with multiple firearms and weaponry.
Thomas Jane initially turned down the role twice, as well as a part in X-Men (2000), as he didn't see himself as a superhero actor. He only became interested in the character after being asked to play him for the second time and he had seen Timothy Bradstreet's artwork of the character.
When the teaser trailer was shown, there was negative reaction to the solid white skull logo which has been the character's trademark in the books. The costume designer changed it to a "worn-down" design that better suited Frank Castle's character in the film.
Five identical Pontiac GTOs were built (two were totally destroyed) for the movie. This muscle car was chosen the film to distance itself from the earlier Australian version of The Punisher (1989) (in which action star Dolph Lundgren rode a motorcycle throughout).
The Castle family house in Puerto Rico are really restrooms/changing rooms located in Honeymoon Island State Park, Dunedin, Florida. State Parks adhere to strict rules about color of their buildings, the restrooms/changing room where re-painted from their original grey to the colors seen in the movie, they remain that color since the movie was released.
Jonathan Hensleigh was dismayed before filming began when he learned that he wasn't going to be given sufficient budget for a top flight action movie. He felt he needed in the region of $64 million but was only given $15 million instead, and only 52 days to shoot the picture. Hensleigh had to rewrite a lot of his original script to accommodate this reduction in budget and shooting schedule.
Thomas Jane returned as Frank Castle in the 2012 short film "The Punisher: Dirty Laundry". Which sees Castle punishing a gang that assaulted a group of prostitutes and Castle giving one of his signature t-shirts to a boy, whom the gang mugged.
John Travolta allowed Thomas Jane to have his name first in the credits and advertising so that he could work on this project. In fact, he didn't mind it at all, allowing Jane to be put over so he can get recognition as the main character.
Despite never actually interacting, Thomas Jane and John Travolta both starred in Face/Off (1997). Jane played one of the inmates at the federal prison in which Sean Archer as "Castor Troy" infiltrates.
When shooting the surprise retirement party for Frank Castle (Thomas Jane) after the success of the major sting, the group of extras behind the table were directed to make simple cheers once Thomas Jane walked in. This scene was shot several times because a certain actor kept fumbling his lines. On one such entrance of Thomas Jane, he commended the extras and told them that he actually felt like they were real and sincere with their praise for him.
Many of the characters, including Joan, Bumpo, Spacker Dave and The Russian, all come from the punisher series "Welcome Back, Frank", written by Garth Ennis and illustrated by Steve Dillon and Jimmy Palmiotti. Timothy Bradstreet illustrated the covers, along with the promotional posters for the movie.
Jonathan Hensleigh wanted the music to be very emotional. When scoring the film, composer Carlo Siliotto saw Frank Castle as a tragic figure stating, "This man, Frank Castle, is somebody who has a slaughtered family. He comes through that slaughter, and becomes a punisher. But he's a sad man - he drinks, and he has bad memories always coming to him. There's a lot in the film, and at times it is like a modern version of classic tragedy like "Othello."
The weapon Castle uses in the final shootout is a Colt M4A1 carbine, a shortened version of the M16 rifle. Castle's is modified with a flat-top upper receiver with a Picatinny-type accessory rail, an M203 40mm grenade launcher , and an Aimpoint M68 Close Combat Optic.
Frank's tenement building was located at the corner of N. Nebraska Ave. and E. Zack St., directly across the street from the Tampa Amtrak station. It was a fairly well known local landmark due to it's unusual shape, but has since been demolished.
Scenes were constantly scaled back or cut to meet budget requirements. Effects scenes were almost always done the old-fashioned way with old tricks replacing new CGI. Jonathan Hensleigh discusses this in the commentary track of the original DVD edition
When Castle is readying himself to administer the coup de grace to Saint, he attaches a shoulder stock to a pistol. This is presumably supposed to be a Glock 18, a version of the Glock 17 9mm capable of fully automatic fire. This is uncertain, however, since the piece never appears again in the film.
The director's cut of the film features a subplot in which it is revealed that Jimmy Weeks (A. Russell Andrews) gave information to the Saints about the Castles in order to settle a gambling debt effectively betraying Frank (Thomas Jane). Frank discovers this and then, in a very dark scene, forces Jimmy to commit suicide. The idea was cut from the theatrical film for pacing reasons.
The Saints and Sinners Club shootout between Frank Castle and Howard Saint's goons was originally longer, but was cut because of pacing and explicit bloodshed. The only two scenes that were altered because of violence were: 1: The point-blank head shot featured blood squirting from the back of a thug's head. 2: The scene in which a thug is dispatched by way of sawed-off shotgun was also cut. The original scene feature pieces of the thug being sprayed from his wounds.
The scene when Howard Saint visits Quentin Glass in his home at night was actually shot in the middle of the afternoon. The evening effect was achieved by tenting up the real-life house that was being used as Glass's home.
The scene in which hot oil is tossed on to The Russian was scaled back due to excessive violence. Originally, blood was supposed to pour from The Russian's eyes, but it was deemed "too much" by the MPAA.
Frank Castle manipulating Howard Saint into murdering Livia Saint and Quentin Glass, by making Saint think that Livia and Glass are having an affair was written as a nod to Licence to Kill (1989) - James Bond manipulates Franz Sanchez into killing Milton Krest, by making Sanchez think Krest hired someone to kill him.
All the piercings that Ben Foster (Spacker Dave) wears in the movie are fake, except for the eyebrow one. In the scene where Will Paxton (Quentin Glass) removes them one by one, a prosthetic was made for the eyebrow one so that it could be taken out without injuring Ben.
In the narrative behind Castle's speech in the final scene. The speech is Castle's warning to the criminals as The Punisher and that if they break the law or kill, hurt or wrong the innocent, he will come after them. Frank Castle is a man who has lost everything and is now on a path on a violent vengeance.