Dawson Casting: Surprisingly little of it for a '90s teen horror film. The only twenty-something cast members playing teenagers were 22-year-olds Shawn Hatosy and Laura Harris and 21-year-old Clea DuVall, all of whom were very close to the cutoff. Elijah Wood, meanwhile, was 17 when he starred in this film, while Jordana Brewster was 18. Josh Hartnett was 20, but Zeke was repeating senior year, making him just a year or two younger than Hartnett (presuming this was the only time he'd been held back).
And Harris technically gets a free pass, seeing as she was actually the alien anyway.