In the original script, a cow was the panthers host, not a dog.
Although the alien that hatched from the dog was a rod puppet, early filmed tests used an actual dog in an alien costume.
Goof:
The bloodstain on Clemens' overalls changes size twice when the governor arrives
Alternate versions:
just before the autopsy, there is a scene with Clemens, Ripley, and Prisoner Kevin walking down the spiral stairs into the morgue where Clemens questions Ripley about her need to acertain Newt's death and also asks her if Newt was her daughter.
just before Ripley enters the mess hall with her newly shaved head after the funeral, there is an interesting little scene that builds character development. It concerns Prisoners Boggs and Rains and their complaints to Dillon about Prisoner Golic being crazy, how Golic smalls bad, and how they don't want to go into the tunnels to work with him. Dillon adamantly tells then they must do their job and have no choice.
in the scene where Ripley asks Clemens if he is attracted to her and he tells her she is very direct, Ripley's reply of "I've been out here for a long time" was not originally included.
in the scene where prisoner Murphy becomes the alien's first victim in the vent shaft, he is singing a different tune than that heard in the theatrical version.
right after the scene were Ripley finds the EEV's flight recorder, there is a scene where Dillon sees Rains, Boggs and Golic starting off into the tunnels. Dillon asks them to light a candle for the dead Murphy.
the scene where the Warden and Clemens meet to discuss Ripley is longer. Clemens tell the Warden that Ripley was member of a combat team who got finished off. The Warden insinuates that Ripley and Clemens are having an affair, then he tells Clemens to get the hell out.
during the scene where Ripley is having a conversation with the badly smashed Bishop there is several intercut scenes showing how the bloody and raving Golic is found by the cook, Eric. Golic is then grabbed by Clemens, 85, The Warden and Dillon and dragged to the infirmary.
when Clemens and Ripley is talking in the infirmary, the tied-up Golic interupts with a few lines about "in this insane world, the insane man must be sane". Clemens sarcastically thanks him.
after the alien has killed Clemens, there is a close-up of Golic stuttering "Magnificent".
in the fire-scenes about 10 minutes were cut out. shortly said: several of the prisoners are seen consumed by the fire. Junior is told to turn on the sprinklers. As he proceeds in his mission, he is attacked by the alien. Junior runs into the toxic waste room with the alien in his heels. Ripley and Dillon closes the doors and they then hears the alien killing Junior. Dillon turns on the sprinklers... Ripley and 85 is having an discussion about religion. 85 says he thinks the rescue team would come at any moment and kill the alien with smart guns... Morse is shaving his head in the infirmary next to Golic. The crazed man manages to talk Morse into releasing him. After Golic gets to know where the alien is, he knocks Morse out cold... Ripley and 85 is communicating with the rescue team. Ripley tests the company's intention by asking permission to terminate the alien. They tell the prisoners to lay off killing it... Golic shows up at the toxic waste room. He tells the guard that he needs to speak to the alien. The guard shrugs him off. Golic slits the guards throat and opens the door. The alien kills him... Ripley and Dillon is talking. Ripley tells the bad news. Dillon doesn't care. Morse runs in, telling them his bad news. The three plus 85 gets to the dump, where 85 blames Morse about Golic...
when Ripley complaints about being ill when they find the dead prisoners by the toxic waste dump, there's an added line where Dillon asks "Where did she go?"
after Ripley's fight with Dillon when he refused to kill her, there's an added line "go kill yourself".
during the scene where the remaining prisoners meet to discuss Dillon's and Ripley's plan to kill the alien, some parts of dialouge is cut out. Most of it Dillon's pep talk to the prisoners and Ripley questioning the Company's intentions.
during the chase scene, when two of the piston guards are running off, Dillon answers "improvising". Ripley finds Eric's dead body, Dillon finds Troy's. Jude falls and cuts himself on his scissors. 85 is meditating as he awaits the company people.
when the company people arrives, it is extended as the asian man asks 85 if he has seen the alien. 85 confirms this and that Ripley has one inside of her. Bishop II says that they already knew that. When 85 sees the cage, he says that they need a bigger one...
when Ripley tries to lure the alien into the piston, she keeps telling it to kill her.
before Ripley is spraying cold water on the buring-hot alien, she cries "For the Last Time." There is no voice-over of Morse telling her to spray it. This was probably added to explain why Ripley is spraying it.
more dialouge between Bishop II and Ripley where II tells her about her courage and the malignancy inside her. The asian fellow tells Ripley about how they would remove the alien. When II asks Ripley to trust him and that she must choose, the scene is drawn out and you can see Ripley agonizing over the decision she had to make.
when Ripley asks Morse to help her, he asks "what do you want me to do?". She answers "You'll know..."
when 85 hits II and is killed, you can see II in pain and shouting "I'm not a droid!"
when Ripley is falling into the molten lead, no chestburster pops through her chest.
after she has jumped, Morse watches down into the lead.
