The opening scene of Swordfish is the most complicated visual effect in Warner Brothers history. It was shot using Matrix-like effects (The Matrix) by Frantic Films of Winnipeg, Manitoba, Canada. The effect has so many composites in it that the producers and director of the film could not determine what was real and what was created by computer.
Trailers, television commercials, and print advertisements for the film all contained "passwords" which allowed viewers to play a contest game on the film's official website. A password also appears in the closing credits. (See "Crazy Credits").
The film was withdrawn from cinemas shortly after the terrorist attacks on New York City and Washington DC on 11 September 2001, due to a scene involving an exploding building.
2600 'The Hacker Quarterly' magazine was approached by Warner Bros. for permission to use their magazine and name in the film. WB was suing 2600 at the time for linking to the DVD deciphering program DeCSS. The magazine said no.
The scene in which the school bus is swung was actually shot by hiring a group of people to sit in a bus, in front of a blue screen, while they swung the bus from a crane. According to the stunt coordinators, the same effect could have been portrayed for half the cost.
Unlike many Hollywood movies, the amount of the ammunition in firearms is depicted correctly. During the chase sequence, Gabriel fires a total of 89 shots from M249 Squad Automatic Weapon, which carries a 200 round box.
At one point during Stanley's attempt to hack into the Department of Defense database, his screen shows six numbers that appear to be IP addresses. (The first is 213.225.312.5.) The numbers between decimal points in an IP address, called "octets", are decimal representations of 8-bit numbers (8 binary digits of either 0 or 1). Therefore, the range of decimal numbers for an octet is 0 to 255, because 11111111 in binary is 255 in decimal. The IP addresses on Stanley's screen each contain one octet higher than 255 (such as 312 in the first example), which is apparently the filmmakers' way of ensuring that no one's real IP address appeared.
Halle Berry agreed to the topless scene - ostensibly for an extra fee of $500,000 - because she wanted to overcome her fear of doing nude scenes. This was on top of her initial fee of $2 million.
John Cusack and Val Kilmer were considered for the part of Stanley. Ultimately, director Dominic Sena opted for Hugh Jackman because he didn't bring too much baggage from other films with him.
Rudolf Martin plays Axl Torvalds, a hacker of some renown in the film. The character is named after Linus Torvalds, a "hacker" in real life, who wrote Linux Kernel, the original code for the open source computer Operating System named after him, Linux. Axl and Linus are both Finnish.
The original screenplay draft had a very different take on the Gabriel Shear character. He was first written as a mercenary whose plan for the stolen DEA funds had him joining forces with military and intelligence figures and planning to destroy corrupt politicians, and had several lengthy monologues in which U.S. agents listened to him and then joined his crusade on the spot. While the funding/covert war angle was maintained, Skip Woods later remade Gabriel Shear into a patriotic agent who seeks to destroy world terrorists, and who kills the Senator and his aide for trying to kill him and stop his plans.