As with the Nostromo and Sulaco from Alien and Aliens respectively, the naming convention used for the human ship (the Verloc) in this game is a reference to another character from a novel by Joseph Conrad, following the fondness for the works of this author of director Ridley Scott who directed the first film.
Actors David Scully and Jen Taylor have done voice-overs in this game. Because of this, the Aliens series-inspired game Halo hired them to be as similar as possible to the series. They even played similar roles (as the "only" African-descended Marine seen in the game, and as the guiding voice in the player's ear respectively).
On the "Alien" plot portion of the game during the "Pursuit" chapter, after the cut scene featuring the androids killing the drop ship personnel, the alien character you play starts out in a blue tunnel. If you listen closely to the audio that is going on in the background, you'll hear the audio from Bonus Features menu of the first Alien DVD release, complete with the Nostromo's alarm, chains clinging together, and even Jerry Goldsmith's score.
After playing the chestburster scene where the player actually eats through the chest of the ill-tempered guard, if you walk towards the closed door that you entered through as a face hugger, you'll hear people on the other side trying frantically to get it open.
The second "Alien" level is named "Surprise" in the menu; a mistake in the introductory cutscene for the level begins by calling the level "Escape". "Escape" is actually the name of the third level. Escape is also the name of the second Alien level in the first game.