Continuity: When Ripley reconnects the dismembered Ash droid, the switch from dummy to actor is blatantly visible. A few minutes later the android is incinerated, at which point the dummy head has reappeared and the android's left arm has disappeared.
Great sites
Quotes
Ripley: Did you ever ship out with Ash before?
Dallas: I went out five times with another science officer. They replaced him two days before we left Thedus with Ash. Hmm?
Ripley: I don't trust him.
Dallas: Well, I don't trust anybody.
Mistakes
Before Lambert is killed, the alien twists its tendrils around her leg, and we see that she has sneakers on. However, when Ripley notices Lambert's dead body (hanging?) she is barefoot. [An editing, rather than pure continuity mistake, as the rest of the scene was cut. According to the novelization, Lambert was actually intended to be shown completely naked and sexually ravaged. Director Ridley Scott had toyed with the idea of creating the illusion of the Alien having raped her before her death. He thought better of it and cut the scene. Still a mistake, but there's why.] See more...
Trivia
Originally, director Ridley Scott wanted "Alien" to have a much darker ending. His intention was to have the alien get back on board the shuttle, rip Ripley's head off and then calmly sit down in her chair and record the final transmission, speaking in her voice. The producers understandably found this a little too extreme, so Scott tried changing it to having Ripley go to sleep as normal only for the camera to pull back out of the airlock's window and reveal an alien egg, in the process of hatching, attached to the outside of the shuttle (after the "Brett/Dallas egg mutation" scene was deleted, this also had to go). See more...
Alien (1979)
Directed by Ridley Scott, starring John Hurt, Sigourney Weaver, Tom Skerritt (add more)
Alien mistakes
Continuity: During the alien chest-burster/death of Kane sequence, Kane's shirt switches back and forth from being tucked-in, to being un-tucked throughout the scene.
Continuity: When the search party goes into the boneship, they are wearing full space suits, and hoods under their helmets. When Kane's helmet is first cut off, he has no hood on.
Alien trivia
When Kane is in the egg pit on the alien ship and shines his light on one of the eggs, the shape we see moving inside is in fact the hands of director Ridley Scott clad in rubber gloves.
When Kane encounters the alien eggs, some droplets of the dark liquid that covers them can be seen falling upwards instead of downwards. This is because the egg was in fact upside down when it was filmed and the shot was inverted to show the otherworldly nature of the eggs.
Originally, director Ridley Scott wanted "Alien" to have a much darker ending. His intention was to have the alien get back on board the shuttle, rip Ripley's head off and then calmly sit down in her chair and record the final transmission, speaking in her voice. The producers understandably found this a little too extreme, so Scott tried changing it to having Ripley go to sleep as normal only for the camera to pull back out of the airlock's window and reveal an alien egg, in the process of hatching, attached to the outside of the shuttle (after the "Brett/Dallas egg mutation" scene was deleted, this also had to go).
Alien quotes
Lambert: I can't see a goddamn thing.
Kane: Quit griping.
Lambert: I like griping.
Ripley: When we throw the switches, how long before the ship blows?
Parker: Ten minutes.
Ripley: No bullshit?
Parker: We ain't outta here in ten minutes, we won't need no rocket to fly through space.
Ripley: Ash, that transmission... Mother's deciphered part of it. It doesn't look like an S.O.S.
Ash: What is it, then?
Ripley: Well, I... it looks like a warning. I'm gonna go out after them.
Ash: What's the point? I mean by the, the time it takes to get there, you'll... they'll know if it's a warning or not, yes?
Alien easter eggs
On the special edition: go to the main menu, highlight special features, press right, and you will get the dossiers for the crew.