During his escape from Ralfi's club, Johnny throws away a handgun once it runs out of ammunition, only to be seen clearly holding it again in a subsequent shot.
When Spider attempts to run "decryption codes" for Johnny's implant, and the camera captures this scene by circling around all the principal actors, the camera casts a shadow on actors and scenery whenever it passes in front of any of the lighting rigs (which are also visible) that illuminate the set.
Much of the Street Preacher's wardrobe spontaneously disappears in-between shots while the character is crucifying Jane.
When the Street Preacher is crucifying Spider, we're shown two separate takes of the Preacher picking up the same scalpel to nail Spider's palms.
The Opening Scroll outlines that the story takes place in the "Second Decade of the 21st Century", but other title cards naming the exact year as 2021 would place the story's setting in the third decade of the 21st Century.
California Doubling: The film was shot on location in Canada, with Toronto and Montreal filling in for the film's Newark and Beijing settings. A number of local sites, including Toronto's Union Station and Montreal's skyline and Jacques Cartier Bridge, feature prominently.
Creator Killer: Both Gibson and director Robert Longo swore off working on Hollywood movies after their experiences here. Longo subsequently went back to directing music videos, while Gibson's only other screen credits to date are a pair of episodes for The X-Files.
The Japanese release is roughly seven minutes longer than the American/International release. Changes include extended sequences, alternate takes/dialogue used for existing scenes, a different Opening Scroll, and a different musical score and soundtrack mix. Scenes NOT in the American/International release include:
Johnny acquiring his "memory doubler" from a contact in the lobby of the Beijing Hotel. Dialogue between the two suggests that Johnny is already aware before he gets to the hotel room that even with the memory doubler his storage capacity would not be adequate for the job he signed on for.
Ralfi's bodyguard who coldcocks Johnny in a men's bathroom remarking afterwards that she hasn't been in the same bathroom in "years," pointing out that she's trans female.
The Street Preacher delivering a sermon about rejecting the organic body and embracing technological implants as part of God's plan for humanity and salvation from the NAS plague. PharmaKom goons come to bring him the preservation chamber with which to store Johnny's head.
Johnny has a completely different reason for "doubling himself" when hacking his own brain to find the last image of the download code. In the International cut, it's so Johnny could survive an attack from the computer virus protecting the MacGuffin. In the Japanese cut, it's so Johnny could survive "looping" the final third of the code through Jones.
Takahashi killing two mooks Shinji had appointed as his "kobuns" after Takahashi says he did not give him permission to have any, as well as berating Shinji for failing to collect Johnny's head a second time.
J-Bone explaining that Jones is a "junkie" and demonstrating that he requires some unnamed drug from a syringe.
An additional scene of Takahashi mourning the loss of his daughter, while observing a holographic projection of her.
J-Bone's distorted visage appearing on Takahashi's Video Phone to encourage him to rebel against his corporate superiors.
An additional lecture from the AI woman, speaking to Takahashi; she appears with long, curly, blonde hair that the character is never seen having in any of her other scenes. In the Japanese cut, this scene is the character's first appearance.
On the other hand, of notable absence from the Japanese cut, making this exclusive to the American release, are the reaction shots of other main characters in Heaven during Johnny's final hacking sequence. We never cut out to J-Bone to deliver exposition to help the audience make sense of the CGI action (e.g. "He's doubling himself"; "Don't worry, that's the double"; etc.), and the CGI sequence just plays out, leaving the audience to try and make sense of it all on their own.
Disowned Adaptation: William Gibson isn't very happy with what became of this adaptation of his own story. Gibson himself, despite being credited as the sole screenwriter, has insisted for years that it wasn't his screenplay that was ultimately produced.
Executive Meddling: According to Gibson, the movie was re-edited by the producers in order to make it more "mainstream". The Japanese release is said to be closer to the director's and Gibson's original vision, although that probably isn't enough to make it good.
The Mockbuster: The low-budget 2003 sci-fi action film Absolon bears striking similarities to the plot and thematic elements of Johnny Mnemonic. Absolon is set in an early-21st century "near future" where half the world has been killed by a viral plague known as "Neurological Degeneration Syndrome" (NDS), and the remaining survivors are dependent on receiving regular treatments produced by a single pharmaceutical Mega-Corp. The film's hero (played by Christopher Lambert, who funnily enough was once in the running to play the lead role in Johnny Mnemonic, before Keanu Reeves got the part; See Also: What Could Have Been) is unwittingly tasked with carrying part of the cure for the plague in his own bloodstream and finding the second half of the cure in three days or less, or else the part of the cure already inside him will kill him. The film also co-stars Lou Diamond Phillips, bearing a vague resemblance to actor Denis Akiyama and also filling a character role very similar to that of Shinji from Johnny Mnemonic. However, in a unique twist on Johnny Mnemonic's premise, there's an important revelation that the cure the hero is carrying in his bloodstream is NOT for the plague—which turns out of have already died out—but a cure for the human body's dependence on the Mega-Corp's continuing treatments.
The film got the Internet both right and wrong; while there is in fact a widespread data network in the film that is used for information and communication all around the world, the interface to access it requires a (implied very expensive) virtual reality rig and is impractical at best and despite the fact that such a graphically intense interface would require a massively wide data pipe just to work, a huge deal is made of ferrying a couple hundred gigabytes from one place to another. And then, despite all this, the spreading of pirate information from the LoTeks who would surely be able to steal the 3D-Internet technology happens by analog TV transmission.
In 1995, 320Gb was massive. By 2015... a card the size of your fingernail can fit 200. This is an upgrade from the short story, which was written in the 80s and used megabytes instead of gigabytes. The first gigabyte sized hard drive released in 1980 was the size of a refrigerator and weighed 550 pounds. By comparison, an 80Gb sized drive with overflow capacity placed in someone's head within 25/35 years would seem like a possible overreach.
J-Bone urges everyone to "get their VCRs ready" when the Lo-Teks are about to broadcast the cure to NAS.
The lack of plasma and HDTV monitors anywhere really becomes apparent when television is supposed to be viewed as a prevalent characteristic in this world.
Faxing is already pretty outdated by today's standards, and the lone fax machine seen in the movie takes something like three minutes to warm up before finally beginning to send a fax. Even 1995 fax machines didn't move that slowly. Given how easy it is for Johnny to track where the fax was going, he might as well have sent three .jpg files via E-mail.
Encrypted E-mail was already a thing people knew about and knew would be better developed over time back in 1995 when this movie was seen in theaters. While physically transmitting encrypted data has become unnecessary, some employers will transfer encryption keys physically via certified couriers if the project is classified in some manner, such as a government contract.
Johnny apparently takes a Concorde jet to Newark. In real life the Concordes were retired in 2003.