The animation of Darth Vader when he speaks to Mohc is 'borrowed' from the X-wing game. A similar animation is seen in a game over cutscene when your pilot is captured and Vader interrogates you.
Similarly. the close-up of Vader's face at the epilogue, is taken from TIE fighter..
The game was developed with the Jedi engine. While similiar to the 2.5D Doom and Build engines, It could handle multiple stories and true up-down perspectives.
Kyle Katarn shares his name with a "katarn", a predator from Kashyyyk according to some Star Wars books and media.
As far as anyone knows, the heavy android "Dark Troopers" were invented as the plot device for this game. Later, the Dark Troopers took on steam by appearing in later video games (Rebellion, Galactic Battlegrounds, etc.), and also in some comics and other media. A Dark Trooper's head/helmet is visible in a level of the expansion pack to "Jedi Knight" called "Mysteries of the Sith". It is safe to say that the Dark Troopers in later media are no where near as difficult as the ones Kyle Katarn went up against in this game.
The third level- planet "Anoat" caused some confusion, as many people believed that this was the system referred to by Han Solo in "The Empire Strikes Back" (when he detaches from the Star Destroyer). In later books and scripts, they say the term "Veronat" or "Varonat". Whether the creators of "Dark Forces" meant for the third level to be in the same system as Bespin remains speculation.
In an issue of Lucasarts' old magazine; "The Adventurer" (that came with games of the era), "Dark Forces" was previewed with screenshots that did not appear in the final game. Among these included a map of a standard Star Destroyer level (the "nose" of the Star Destroyer is very identifiable), an undisclosed Imperial base/Death Star/Star Destroyer level (with a very steep vertical drop), and an abused urban setting (that appeared to have an unfinished, bland sky overhead). Also, the emblem on Kyle Katarn's datapad was different at the time.
'Dark Forces', as a series, was named #5 of the Top 50 Games of all time, by the editors of PC Gamer magazine in the October 2001 issue.
Both the US and the German version were banned in Germany (German: 20.10.95, US: 30.09.95)
Dark Forces used the legendary scream sample. If you tripped (Or jumped) off a tall structure Kyle Katarn would scream: "Uuuuarrrgggghhhh!!!!" This scream sample has been used in countless of productions, and there are countless of websites dedicated to the art of spotting it.
The original idea was that Denny Delk (the narrator) would read the Star Wars scrolling text, but it was cut out. He actually recorded the lines. You can extract the sound files of these lines with one of the modding programs, available at massassi.net
Also, in the intro, there was a movie showing Kyle Katarn loading his weapons, but this was cut out too. It can be found in the game demo.
The Imperial Blaster Rifle sprite was used in Star Wars Rebel Assault 2 on the second CD.
Dark Forces was voted #46 overall in PCGamer Magazine's Readers All-Time Top 50 Games Poll (April 2000 issue).
Max from Steve Purcell's duo of Sam and Max (who star in their own LucasArts game, Sam & Max Hit the Road) makes a most unusual cameo appearance in Dark Forces.
On the ice level, keep your map up during your investigations of its perimeter. You'll notice on the map one structure that looks very similar to the infamous rabbit.
Ewoks also make appearances in the form of a few chained up who make fun of you (and you can shoot if you're one of those Ewok hating Star Wars fans) and the 'Ewoks suck' graffiti you'll find in the some of the darker corners of the Imperial facilities.
Two star wars action figures were actually released based on characters from this game. One was the main character Kyle Katarn (whose image was lifted from the game, but they added a beard so he'd look more like the Jedi Knight version of him). The other was General Mohc (the final boss) in his specially modified Phase III Dark Trooper battle suit.