Character mistake: When they're on the island and the INGen helicopters are flying in, Jeff Goldblum takes the binoculars and looks through the wrong end. (00:32:30)
Character mistake: During the scene in which they are all arguing whether or not film sequels are better than the original or not, someone says Sigourney Weaver's classic line from the movie Aliens: "Get away from her you bitch", and Randy makes a smart comeback and tries to correct him by saying "I think the correct line was 'stay away from her you bitch'. This is a film class, right?" Wrong - the first guy was right. This line is truly unconvincing for the Randy character, being a big movie buff and all. Jamie Kennedy decided to improvise as Joshua Jackson actually made the initial mistake by saying the wrong line, causing a different mistake. (00:16:25)
Character mistake: When Ripley asked the doctor how they "got" her, he replies from blood samples on Fury 16. This is in reference to the planet in Alien 3, but it was called Fury 161. (00:11:00)