Which shot seems dodgy to you?
No, in the youTube fan-extended edit I linked to, it’s at 00:04 and another at 00:08, though I’m not sure if the take that’s in the released film is the same as either of the ones shown there.
The thing is, just like with CG animations of people, our eye is so finely attuned to the nuance of human movement that we can easily tell when there’s an actual person inside the performance.
It’s the same with the test footage mentioned earlier of Bolaji creeping through the half-finished Nostromo set, and costumed in only a crude banana head and his skivvies. I think Scott could tell from that early test that there was no way he could film a full body actor walking from A to B and successfully disguise the human inside, no matter how good the suit was. If you compare all the early storyboards of what Scott thought he could achieve, with what’s in the actual film, you can see that there are no shots of the alien actually ambulating anywhere—it just couldn’t be done without giving the game away. I guess it’s one reason why when it’s pursuing Dallas in the airshafts we get to watch it moving only as electronic blips on the motion tracker. Kind of like the shark in Jaws
when it’s chasing the boat; it looked so hokey Spielberg decided the better option was to show us the barrels on the surface instead (being towed around by the shark).
Speaking about movement, and looking at that YouTube fan-edit again, it’s interesting how the close-ups of the animatronic head only really come alive when there’s additional movement in frame, such as the dribbling drool and the smoke and steam puffs being blown through frame, (and in Brett’s death scene, all the rain and rivulets of water). There are outtakes in which there’s none of that, and they just seem so dull.
I give it to Scott, he really knows how to dress a scene up to bring it to life. Although the strobe lights in the Ripley escape run were a bit overboard, IMO.