It would be interesting to see the brood, but it would have to be a take-off of the short story arc where Havok and Polaris (not introduced on film yet) find out a ship carrying the brood crash-landed on earth. But it might seem too much like an Aliens rip-off.
I also thought that some parts of the movie was a game of "Let's see how many obscure characters we can shove into a scene."
Also, another major gripe, Juggernaut is NOT a mutant!!
I remember the first time I read the scene where Havok and Polaris find the Brood ship. I recall it took Claremont several months to get back to that story arc. I really enjoyed his style of story-telling.
I can just imagine that the film makers packed a lot of mutants into X3. They did so in the first two as well and it did seem to detract from the story.
Someone told me Juggernaut was in this movie. I wondered if there was some background given about his origin.
And how would trying to explain Juggernaut's powers as having been mystically bestowed by Cyttorak (via a magical ruby) have helped the movie? Some things have to be streamlined and even altered for the film version. "X3" also doesn't give any indication that Juggernaut has any ties to Professor X, while in the comics he's Professor Xavier's step-brother. Does it matter? Not really, because it isn't relevant to the film's main plot.
I found the high-profile deaths in "X3" a bit surprising, but keep in mind how many mutant characters have existed over the history of the X-Men since their first appearance. Beast, Iceman, Colossus, Shadowcat, Havok, Polaris, Banshee, Angel, Gambit and many more are still available to take center stage in future installments. And as the coda after the credits demonstrates, improbable resurrections aren't out of the question.
I liked the movie, even its new explanation for the out-of-control Dark Phoenix version of Jean sans any mystical or extraterrestrial baggage. We'll never get a filmed version of the comics as written, but that's not the purpose of the films, which have to stand on their own in a form that non-fans of the comics can easily grasp. It was a fun, action-filled story that served to advance the series and leave many options for future entries. X-Men fans who aren't hung up on the minutae of continuity should check it out.