Followed up on when Stavrou actually gets the bus to work.
Stavrou: "Yeah baby! NEWARK, represent!"
As the team tries to drive the bus through enemy territory, they just keep smacking into abandoned vehicles.
Nantz: "Try to miss at least one of the cars, Stavrou."
As the Marines line up to board the Sea Knights:
Guererro: Harris, what's your take on this?
Harris: I dunno, extraterrestrial?
Imlay: You mean, like from space?
Stavrou: No, from Canada.
During the final shootout, Harris and Santos pin an alien, who manages to punch Santos in the face before dying. At which point Santos shoots it some more and shouts at it:
During the sewer escape, one of the Marines drops a grenade down the manhole. A pursuing alien stops, picks the grenade up, and looks at it as if thinking 'What the hell is this thing?' right before it blows up in its face.