Writer David Webb Peoples has said that Soldier is a "side-quel" to Blade Runner (1982) (which he also wrote) because it takes place in the same universe, and in fact the vehicles used by the Blade Runners - spinners - are also used in Soldier. The premise of Soldier was actually based on an unused opening scene for Blade Runner, where a group of Replicants are dumped and left for dead on an Off-world colony. Both films were released by Warner Brothers, and both were box-office failures that gained a cult following after being released on home video.
According to Paul W.S. Anderson, Kurt Russell worked out three or four hours a day for eighteen months to get himself into the "pumped-up" condition he displays in this film. Anderson says the making of "Soldier" was actually postponed to allow Russell to do this, because Russell thought it was so important to Sergeant Todd's character; Anderson made Event Horizon (1997) in the interim, while Russell made no other movies during that time.
While listing the weapons on which Todd is trained, you can see he is capable of using the "Illudium PU36 ES,M" otherwise known as the Illudium PU36 Explosive Space Modulator. This is the same weapon Marvin the Martian is always threatening to use on Earth, in his Bugs Bunny cartoon appearances.
Among the garbage on the planet is the U.S.S. Franklin Delano Roosevelt, the F-117X Remora from Executive Decision (1996), a spinner from Blade Runner (1982), and a piece of the Lewis & Clark from Event Horizon (1997).
Among the snakes used in the film are Thai vipers, and are extremely venomous. Stitches can be seen around their mouths to render them safe. Nevertheless, when Kurt Russell is seen to be holding one of the snakes, it's not really his hand. The snakes were deemed to be too dangerous to be held by him.
Kurt Russell sustained a broken ankle during the first week of filming, and got a week off. When he came back, all of the scenes where he was laying down were filmed. They followed that with the sitting-down scenes, then the standing-still scenes. Finally, the action scenes were shot. The last scene filmed was the "running" scene between Todd and Caine 607 near the beginning of the movie.
David Webb Peoples started writing the screenplay to Solider while Blade Runner was being filmed. As the screenwriter of both films, he has long maintained that they are set in the same universe. Director Paul Anderson agrees, and says that if Kurt Russell's character were to go to Earth, he would have encountered Harrison Ford's Deckard.
An implication in the film is that the genetically-engineered soldiers meant to replace Todd and his fellow soldiers are in fact replicants, continuing a theme from Blade Runner. The 2017 short film 2036: Nexus Dawn, set in between the original Blade Runner and its 2017 sequel Blade Runner 2049, implies that Nexus-9 replicants were developed in 2035, the year in which Soldier takes place.
Mekum wetting his pants when he sees Todd alive and well, and back to punish him, was not in the original script, it was improvised on set. The urine dripping out of Mekum's pants was actually pineapple juice.
The Trinity Moons screen near the end of the movie, also includes references to "Eminiar 7" from Star Trek: A Taste of Armageddon (1967), and "Kessel", possibly referring to the Kessel Run, mentioned by Han Solo, in Star Wars: Episode IV - A New Hope (1977).
Freeze frame the "Trinity Moons" data readout display in the closing scene and you will find several references to "The Hitchhiker's Guide to the Galaxy". The "Top Archive Specifications" comes up with ZZ9.Plurl.ZA (the sector in which Earth is reported to be) which comes up in Zaphod mode. On the right under "Search Results" you can see "Slartibartfast" complete with an "HHG" reference number.
Todd's Unit Statistics reference the Dungeons and Dragons Ability scores: STR, DEX, INT(L), WIS, and DEX. It also shows stats for his damage (DAM), hit points (HTPT), language (LNG), loyalty (LOY), and even RSR, which means "Resurrection."
When first submitted to the MPAA, the movie got an NC-17 rating, and some of the violence had to be cut down for R-rating. The eye gouging scene in the fight between Todd and Caine in the beginning was the most heavily cut scene.
Original script by David Webb Peoples was written in 1982 or 1983, and it was originally titled The Base. Director Ted Kotcheff and Sylvester Stallone were involved in the project around that same time, right after they made First Blood (1982), but once Stallone left, and Clint Eastwood, next actor who they had in mind for main role also left, the project was cancelled, and after the script went through many different studios next 15 years, it was finally re-written and turned into Soldier (1998).
The trivia item below may give away important plot points.
In Connie Nielsen's later film Gladiator (2000), her character Lucilla falls in love with the Roman soldier General Maximus, after the death of her husband. In this film, Todd, a soldier, falls in love with Sandra (Nielsen), whose husband Mace was killed.