Deliberate mistake: After Ash's body is incinerated, the interior walls of the Nostromo appear more metallic and grey than they were before. According to Ridley Scott, this was done deliberately to make the alien's presence appear more menacing.
Alien (1979)
1 deliberate mistake - chronological order
Directed by: Ridley Scott
Starring: Sigourney Weaver, John Hurt, Ian Holm, Tom Skerritt, Harry Dean Stanton, Yaphet Kotto, Veronica Cartwright
Continuity mistake: In the shot of the alien's tail wrapping around the back of Lambert's legs right before it kills her, the floor is different to what it was before, there is water suddenly falling from the ceiling when there wasn't before and her trousers have changed from white to blue. This is because that shot was originally intended to be used when Brett was killed.
More quotes from Alien
Trivia: Ripley abruptly yelling at Parker to "Shut up!" is not in the script. Fans and industry gossip have long speculated that this was Sigourney Weaver breaking character in frustration and she was in fact telling Yaphet Kotto to "shut up" so she can finish her lines. The sequels 'Aliens' and 'Alien 3' both feature scenes where one of the normally cooler-headed protagonists suddenly snaps at a ranting character to "shut up!" in apparent reference to this moment. (01:16:50)
Question: What exactly is the space jockey and why haven't we seen it in the other films except its fossilized self sitting in the what I call the laser gun?
Answer: Other theories, mostly developed in the comics derived from the original franchise, assume the xenomorphs were biological weapons conceived by the Space Jockeys for some interstellar war of theirs. Hence, the crescent-shape derelict was just a bomber, full of eggs and operated by a single pilot to minimize risks of accident with this mostly dangerous cargo. - what just happened though.
AKA, the plot of Prometheus.
Answer: It's another race of space alien that is also subject to infection by the Aliens. This particular one was infected and moved as far as it could from its race's known space and broadcast a warning before it died. The presence of eggs in the hold may indicate that it was a research ship. The race was never used in other Alien movies because it adds a new dynamic to the plotlines: two alien species, locked in mortal combat and neither particularly friendly with humans. In the Alien pseudo-prequel Prometheus we learn these beings are known as the Engineers and have interesting ties with both the aliens and humans as well.
Phoenix