Trivia: The dead Xenomorph on the roof where Rook is, is the very same one killed by Ripley in Alien.
Suggested correction: I'm not really sure if this quite counts as trivia, as the movie quite literally comes right out and tells us that it's the exact same Xenomorph that Ripley ejected into space at the end of the original film, and we even see Weyland-Yutani finding it in the opening scene.