According to Dave Tripet, the executive in charge of production for the first three movies, this film originally started out as a spoof of Apollo 13 (1995). A senior Trimark executive saw the promo art for Apollo 13 and immediately had artwork made up replacing Tom Hanks's face on the poster with the Leprechaun's face, and this is what started the script work for the movie.
The sound of the doors opening and closing are taken from the original DOOM video game, where it was the sound of the elevators.
The title character is never once in the film referred to as a Leprechaun. He is only called "alien," "monster," "bastard," or some combination thereof.
The film takes place in 2096.
Leprechaun uses a lightsaber to dispatch the marine Lucky, Warwick Davis himself has appeared in several 'Star Wars' movies, most notably as Wicket the Ewok in Il ritorno dello Jedi (1983).