During the fifth minute of the movie the number 1138 can be seen on the computer screen. Seconds later again the same numbers but in different order - 1381. It's a reference to George Lucas' cult masterpiece "THX 1138".
Ussal is Referred to as Roj Blake Ussal. This is a tip of the hat to the Character Roj Blake, the titular protagonist of Blake's Seven. Blakes character was the Skipper of the Liberator and his No 1 was Kerr Avon, played by Paul Darrow who cameos the part of a computer in Battlespace
The weapon Mara aquires after hitching the ride on the rocket is none other than the ubiquitous M41A Pulse Rifle favoured by the Colonial Marine Corps of Aliens.