Christopher Lambert's character is billed as John Henry Brennick, however during the scene where ZED is processing Brennick into the fortress, he is referred to as "Brennick, John W.".
The nose blood from Brennick's short time in space without a suit disappears after he closes the tunnel's airlock during the rapid decompression from the airlock chamber door blowout.
At approximately 12:26 into the film when Susan is speaking to Peter Teller at the end of the video transmission the screen shows the webcam feed is actually using Hauppage WinTV and returns to the Windows desktop (showing many other bespoke applications designed for the film). The version of Windows installed is Windows 98 and you can see the free trial for AOL on the desktop.
The movie is supposed to take place 7 years after the previous one (after John's son was born) yet, in this movie, his son is 10 years old.
When Brennick meets Teller. Teller states that he was the prison director in charge of the 1st Fortress, which Brennick and Karen escaped. In the original film, the prison director in charge of the original Fortress was Poe (Kurtwood Smith), who was killed during Brennick's escape.