One obvious point to note: While O'Bannon received screenplay by credit, this draft reflects the writing style of Walter Hill (especially) and David Giler. Reflective of what Hill calls his "haiku style" of writing. For some background on that, you can go here toa post I did comparing the style of Alien and Wall-E.

A classic suspense scene from a great movie.

The movie is vastly superior to the written script in this scene for a variety of reasons all falling under the heading of TENSION.

The script attempts a weaker form of scare tactic by showing the alien pawing at air close to the unaware Dallas. I think it is far more effective to leave the audience in the same frame of reference as Dallas (ie: where the F*** IS IT!?).

The precursor of finding the slime is a great addition which further heightens tension. We now know it is there, but where?

I also like the humanizing addition of Dallas showing great fear not present in the script; “Uhhh, am I clear? I want to get the hell out of here.“ Here is a character that we as an audience have looked up to as a leader and voice of calmness and rationality. If he is scared, then we are terrified as we continue to lose our psychological mooring.

But Lambert (Veronica Cartwright) deserves a great deal of credit. Her movie dialog is far, far more compelling than the script. Comparing script to movie, we identify with her fear in the actual voice-overs: “Are you sure it’s not there, I mean It’s got to be there...” This is just a tad more compelling than “It’s clear alright, but I’m still getting two blips…“ The single most powerful part of the scene is how the (Sorry, but you’re going the wrong way) is delivered. The script is less effective. The better way to realize the mistake is by showing Dallas’ action while hearing the terrified Lambert deliver the punch line off-screen “nooo, not that way, the other way… ”

I am not a fan of cheap ‘gotcha’ scare tactics, and the final payoff (alien with outstretched arms) is not one of those. It is the perfect culmination of a terrific stretch of tension. I prefer the Dallas POV over the scripted “a hand reaches up” with off-screen screams. A perfect ending to a perfect scene.

@ZoeTheCat: That is some fantastic analysis. I hope you don't mind, but I'm going to update the OP with your thoughts. You zeroed in on my thought exactly: By keeping the point of reference tight - Dallas and Lambert - it adds to the claustrophobic feel of the moment, our own sense of impending doom, and generates a lot more tension than indicated in the script. Again great analysis!

And for the record, I know everyone talks about the alien-bursting-out-of-the-chest scene as being so shocking, but it was this scene with Dallas in the air ducts where I literally jumped out of my seat in the movie theater when I saw Alien for the first time. Scared the crap out of me!

Hope I'm not too late for this discussion.

I wonder if the haiku style of writing, while fantastic for the early portion of the script, doesn't heighten the tension enough for the suspenseful scenes.

Could a writer modify narrative voice and get a way with it? Are there any examples of this?