So, the latest special edition of SFX magazine is a top 100 science fiction and fantasy films, as voted for online by 10,000 of its readers, so quite a definitive popular choice award. There are, IMO, a couple of surprising omissions - only the first Back to the Future film is included, but neither of its sequels, despite all three of the original Star Wars films being in there. Personally, I'd rate BTTF II as superior to the first film, but anyway. Also, I suspect a meme coming on ("how many of these films have you seen?" - at a quick glance I reckon I've seen about half of them, with at least a couple on my "list of films I'd like to see at one point"; one of them's on my Amazon wish list, actually.). But that's not the point.
Thing is, there are a couple of films that I don't really think belong in the list. Not because I don't think they're any good - one of them I absolutely passionately love, and the other one I hugely enjoyed - but because I'm not sure they really count as sci-fi or fantasy. One of them's Kick-Ass, which yes, is a superhero film, but the whole point is that the superheroes don't actually have superpowers, they're just people in suits. Well-trained people in suits, but nevertheless.
The other is The Truman Show which...I just don't really see how it can be considered particularly science fiction. It's fiction, certainly, and has at its heart a particularly outlandish concept, but nothing that for me says science fiction.