DALLAS: You get what you're contracted for just like everybody else.
BRETT: But everybody else gets more than us.
As soon as we're introduced to this community, it is clear that things are less Star Trek than Metropolis. Brett and Parker are clearly the "lower class citizens" of the Nostromo and receive less of a bonus than the rest of the crew.
PARKER: You ever notice how they never come down here? I mean, this is where the work is, right?
Parker's quote here squarely places Brett and him as a member of the "working class" while the rest of the crew would be the bourgeois administrators. It is very mini-Marxist aboard the Nostromo.
RIPLEY: Ash, that transmission, Mother's deciphered part of it. It doesn't look like an S.O.S.
ASH: What is it?
RIPLEY: It looks like a warning. I'm going to go out after them.
ASH: What's the point?
We've seen a lot of self-interested motivation when it comes to the crew of the Nostromo. Brett and Parker want their bonuses, and Kane's curiosity pushes the crew to continue on exploring. Here, for the first time, we see character acting for the good of the group rather than for herself. Sure, Ash stops her, but it's a start.
RIPLEY: Ash, when Dallas and Kane are off the ship, I'm senior officer.
ASH: Oh, yes, I forgot.
RIPLEY: You also forgot the science division's basic quarantine law.
ASH: No, that I didn't forget.
RIPLEY: Oh, I see. You just broke it.
ASH: Look, what would you have done with Kane? His only chance of survival was to get him in here.
Ripley continues to make decisions that are best for the group, although this one is a rough one. What we're curious about are Dallas's motivations. Does Dallas think he is doing what is best for the group—that is, rescuing Kane? Or is he still thinking about Dallas's needs, i.e. not having a guilty conscience when this is over?
BRETT: Back to the old freezerinos.
KANE: I've got to have something to eat before we go back.
PARKER: I need something myself.
DALLAS: Yeah. One more meal before bedtime. I'm buying.
PARKER: Hey, that's a break.
Here, we have one of the moments when the group genuinely comes together as a community. Not surprising, the celebration is connected with the idea of food, the only force powerful enough to get bitter family members together around the holidays.
PARKER: That damn Company! What about our lives you son of a b****?
ASH: I repeat: All other priorities are rescinded.
Speaking of self-interest, it turns out the Company was using the crew to get what it wanted, a shiny new alien species to test on. Here, the Company's self-interest operates on a larger, more evil corporation scale, but it's the same impulse that motivates all the other characters—except maybe Ripley.
RIPLEY: We're going to blow up the ship. We'll take our chances in the shuttle. Blow up the ship.
Notice in this scene that Parker and Ripley stand center frame together and look at each other eye to eye. The class divisions that separated them before have vanished—or, at least, been set aside—to focus on a new, uniting goal. They're going kill them an alien.
RIPLEY: I got you… you son of a b****.
Ultimately, the community entirely breaks down. All of the crew other than Ripley have been killed and the Nostromo—the link between Ripley and the larger community of the Company—has been destroyed. Ripley stands alone. Civilized community proves unable to survive the horrors of nature. Welcome to the post-apocalypse.