Johnny throws a gun away after it runs out of ammo. In the next shot, he can be seen still holding the gun.
In the beginning, Johnny wakes up with an alarm clock informing that the date is 17.1.2021. Later he tries to seek from the internet a fax that was sent the same day, but searches with the date 15.1.2021.
In the final scene, Jane has a stream of blood from different places above her left eye. The trickle also changes length.
The street preacher's wardrobe changes between shots when the character is impaling Jane's palms.
The date on the screen in the New Darwin Inn reads "Thursday, 17 January 2021". January 17, 2021, was a Sunday.
The opening scrawl mentions the second decade of the 21st century, but the date stamp once the movie begins says, "The Internet 2021". 2021 would be in the 3rd decade of the 21st century.
Most of the guns are actually paintball guns. Brand names of several paintball makers are clearly visible at several points in the movie and you can often see CO2 blasts when the guns are fired.
The "street preacher" being run over by Spider's van is clearly a dummy figure dressed as the character.
All Chinese text in Beijing is in traditional characters, despite the mainland Chinese government having changed to simplified characters already in 1956, 39 years before the production of the movie.
When Spider is explaining to Johnny the cause of NAS.
When Spider has Johnny in the chair in the hospital as Jane looks on, the camera encircles all three. As the camera passes behind Spider, you clearly see the camera's shadow on Spider's back as it slowly swoops by.
When the cybernetic arm of the bartender is destroyed, he feels pain, but this should not be possible since this is an artificial prosthetic and not an organic replacement with nerve endings etc.
The subway tunnel seems abandoned: there's trash lying around
the track and nobody else in the station. The tunnel lights and station lights might be lit because the Loteks want to make sure they can escape that way, but why are the signals still working?
Takahashi calls Dolph Lundgren by his real name when hiring him for the hit job on Johnny.