(at around 35 mins) When Stony opens the door and gets stabbed and his blood sprays in Kinsa's face, she screams. According to the audio commentary, the effects guys weren't supposed to spray the blood into her face. She was screaming not because she just saw her boyfriend die, but because the fake blood was burning her eyes.
The "virtual '80s" scene was originally meant to be much more detailed, including a number of topless women playing volleyball. One idea even included the appearance of Pamela Voorhees, Jason's mother, and even went so far as to have Jason attack her, showing the extent of just how evil he had become. The latter idea was dropped.
Betsy Palmer was doing a play in Toronto at the time Jason X was filming. According to Palmer, one of the producers contacted her about possibly reprising her role as Pamela Vorhees. They did not come to an agreement, and the character was not included in the film.
The name of the primary ship in the film is the "Grendel" which is the name of a monster in the Old English poem "Beowulf". Grendel was a direct descendant of Cain from the Book of Genesis, a monster described as half-troll, half-ogre. Like Jason, Grendel rose from a lake in search of victims and seemingly could not be killed. Also, in their fight, Beowulf rips Grendel's arm off, and in the movie, when Kay-Em shoots up Jason, the first thing he loses is his arm.
Because Jim Isaac wanted the acting in his film to "blow every other Friday movie out of the water." The associate producer videotaped the rehearsals on a camcorder for Isaac, who would view them afterward to get ideas from seeing his characters in action. The problem was with all the script re-writes a lot of the time Isaac didn't even know if what the actors were rehearsing was still going to be in the movie (most of it wasn't).
One of the things which won over everyone to the concept of Jason in space was the idea of the kids seemingly killing the hockey mask bastard halfway through only for him to be recreated into something even scarier via futuristic technology. The mechanism of this change ended up being nanotechnology, an idea screenwriter Todd Farmer lifted from Virtuosity. However, the actual concept of an UberJason predates Jason X.
(at around 39 mins) Brodski mentioned a gun while the soldiers were suiting up called the "BFG". This sci-fi gun is well known to players of the PC games Doom (1993) and Quake II (1997) as the most powerful weapon. "BFG" is an acronym for "Bio Force Gun" or "Big Fucking Gun", as some called it.
(at around 15 mins) The space debris floating in space has "Cunningham Realty" written on the side. This is a reference to the name of producer Noel Cunningham, the son of executive producer and maker of the original Friday the 13th (1980), Sean S. Cunningham.
Jason X is the first Friday the 13th film to be rated '15' in the UK. Although Friday the 13th parts 2,3 & 6 were originally rated '18' they were altered to '15', part 6 in 2002 and parts 2 & 3 in 2008.
Neither the Casting Director nor the Director initially wanted to do the virtual reality scene. Cook was so adamant the scene was nothing but gratuitous nudity that she refused to cast the roles of the two topless girls, relegating those duties to her casting assistant. Isaac agreed that it was clearly just nudity for nudity's sake, and the only way he could personally justify it is if they had fun with it and made it really silly.
Jason X originally meant to double that by having two couples survive - Kay-Em 14 (well, her head at least) and her creator on one side, Rowan and her love interest on the other. However, 4 days into rehearsal they looked at the script and realized they had no real use for Rowan's male love interest character even though they'd already cast someone to play him.
During Jason X's development process, director Jim Isaac, producer Noel Cunningham (Sean's son), and screenwriter Todd Farmer kicked around any scenario they could think of it, typically "Jason in [insert blank] (the hood, snow, underwater, the arctic, in L.A. fighting gangs, on safari)." They even considered something involving the NASCAR circuit. Farmer suggested "in space" because he knew Freddy Vs. Jason was on the way, and it'd be best if Jason X was set after the events of that epic battle. So, they needed to jump into the future, and going into space certainly did that. They were a little scared of doing a horror sequel in space [see: Hellraiser, Leprechaun, and Critters.], but they thought it could be fun to do a mash-up of Ridley Scott's Alien and James Cameron's Aliens with not one but two strong Ripley-type females on a ship of bad-ass space marines hunted by Jason instead of xenomorphs.
The original script featured a scene where two space truckers would find the chamber before their comrades did. Jason would awaken, escape and have them take Rowan aboard where he follows them. Another idea coming from this was to have a party in zero gravity to celebrate saving her.
The trivia item below may give away important plot points.
Dallas first confronts Jason, his head is slammed into the bulkhead. In "Drive Angry"(2011) he is again killed by a supernatural being, The Accountant whom slams him against the wall smashing his face with a broken Louisville Slugger wood bat.