It's hard to believe it's been three decades since "Aliens" burst into theaters -- and into the hearts chests of fans across the globe. But for the past 30 years, the H.R. Giger-designed interstellar demons at the center of director James Cameron's classic movie have remained firmly entrenched in the annals of sci-fi and horror as one of the most enduringly popular and frightening faces of terror in film history.

Cameron reunited with the cast in Hall H at Comic-Con International in San Diego to reminisce about the making the sci-fi classic. He was joined by producer Gale Anne Hurd, and actors Sigourney Weaver (Ripley), Michael Biehn (Hicks), Bill Paxton (Hudson), Paul Reiser (Burke), Lance Henriksen (Bishop), and Carrie Henn (Newt) to share stories from their time creating the film, and to lament at least one missing cast member and her creator.

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Cameron noted that someone was absent from the panel: the Alien queen. Cameron paid tribute to the queen's creator, Stan Winston, who passed away in 2008. "Stan was a great friend and colleague," Cameron said, explaining that he originally tested the queen's movements and choreography in the parking lot outside Winston's offices with ski poles and large garbage bags. The final queen was manned by two men inside and 14 operators. "It was just rubber and fiberglass," he said. "We believed it was real because Sigourney made us believe it through her performance."

Weaver, who was nominated for a Best Actress Oscar for her portrayal of Ripley, was asked about what it was like to be known as one of the screen's toughest heroines. Weaver replied that in real life, she is hardly so tough, and can't even bring herself to watch "The Walking Dead," which is produced by Hurd. "I am so suggestible, that I would start to see zombies everywhere." She noted that the writing and the realness of the performances of her co-stars is what made her performance so believable.

A clip from the film was shown where the characters are regrouping after the initial alien attack and Ripley suggests nuking the surface of LV-426 while Burke tries to calm everyone down. The clip also features a panicked Bill Paxton, who utters one of the signature lines in the film. After the clip concluded, Paxton said "I only have three words to say: 'GAME OVER, MAN!'" which elicited a roar of approval and laughter from the audience.

Paxton said he was concerned about his portrayal of Hudson. "It's hard to sustain a guy who's always scared. Thirty years later, I can look at it and I think my performance is okay. But at the time, I was really nervous. I thought the character was going to wear out his welcome. Now I can see that the Hudson character was used as a pressure release valve."

"That's exactly what it was," agreed Cameron. "It's a measure of the tension of the film on the audience, and it gives them an ability to laugh."

"I wish it would have given me the ability to laugh," Paxton quipped.

Cameron noted that Paxton's death scene, where he goes down fighting, was heavily improvised, and that the actor said something different for every take. Because loud machine gun fire was taking place during the lines, Paxton had to redub them later on, and because all of the takes were different, it proved challenging trying to figure out what he was saying.

Cameron also pointed out that the scene where Henriksen's android character, Bishop, grabs Hudson's hand, places it on a table with the fingers spread apart and proceeds to take a knife and quickly stab the table in-between his spread fingers, was originally meant to be sped up in camera. That approach was nixed because they used a take that's Henriksen actually moving the knife that fast.

Biehn talked about how much he loved the relationship between Hicks and Ripley. Cameron joked "I think it could have gone somewhere if (David) Fincher hadn't killed you off [in 'Alien 3']."

Henn, who left acting and is now a fourth grade teacher, mentioned that a lot of her student's parents show up to parent/teacher conferences with DVD's for her to sign.

Cameron said he is still haunted by a moment of filming with 10-year old Henn, in which, as he applied goo and slime to her face, she looked at him and said, "You know, it should be illegal for you to be able to do this to little kids."

Henn then related a story of having to go back to her hotel, covered in the slime and goo during Christmas season while a black-tie holiday party was going on, and being traumatized by the looks the party guests gave her in the elevator as they slowly moved to the other side.

Reiser said he was jealous that he didn't get to go to boot camp with the other actors who trained to play marines. "They had all the equipment, and all I had was a little notebook and pencil." He also said that he never viewed his character as the bad guy. "You say 'bad.' I say 'misunderstood.'" Henn joked that she didn't like that she had to sit next to Reiser on the panel. "He tried to kill me!" she said, laughing.

Asked about the delayed Ripley-centric "Aliens" sequel Neill Blomkamp wrote, Weaver explained that it was put on hold until Ridley Scott finishes and releases his "Alien" prequel and "Prometheus" follow-up, "Alien:Covenant." She talked about the project's origin, saying they started talking about it on the set of "Chappie" which they worked together on in 2015. "We started talking about how the series left Ripley. Blomkamp was a fan who grew up in South Africa and loved the movies so much that he broke the tapes. I had never wanted to do a fifth movie. I didn't want to go to Earth [which is what previous sequel ideas were], because I thought Earth was boring. Four months later, I get a script that was so amazing and gives the fans everything they are looking for, plus innovates in a lot of ways.

"He has work to do, and I have work to do," Weaver added, referring to Blomkamp's "District 9" sequel and her commitment to the three "Avatar" sequels. "I am hoping when we finish those jobs we will circle back and start to do it."

"Aliens" is available on Blu-Ray from 20th Century Home Video. A new 30th Anniversary Edition is expected later this summer.