For the record, I was wrong, y'all are right. Thanks for all the, um, colorful feedback. In my defense, I had tried watching this Riff 3 times with different copies of Alien, at least one of them clearly labelled Director's Cut, without success; I was in a dark, angry place and pages like this one at Amazon (
http://www.amazon.com/Alien-Directors-Cut-Sigourney-Weaver/dp/B00011V8IQ) certainly didn't help what with putting the text "Alien (The Director's Cut) (1979)" as the heading of the page. I've rented copies of Alien, "borrowed" a few, and even paid real money for 3 copies of this movie just so I could watch this track and apparently I still haven't managed to get it right. Suffice it to say its a bitter subject.
I think I may (fingers crossed) be able to do so soon now that I have a copy that says Director's Cut on the package. Actually the DVD menu for this copy looks just like the one I remember seeing when I first tried watching this; it offers the choice between the theatrical cut and Director's Cut; I tried both before and neither one seemed to fit. I've redownloaded the Riff as well just in case I had downloaded the PAL version by mistake, so maybe it'll work this time. I own a total of 20 RiffTrax so far and none has given me this amount of trouble.