required reading: Drive to make Hollywood obey the laws of science | Film | The Guardian
there needs to be some sort of distinction between Space Opera (e.g. starship troopers, star wars: set so far into the future that stuff just works and doesn't require explaining e.g. warp drives) and Sci-Fi (e.g. a scanner darkly, and at it's worst The Core, which is just utter, utter sci-lies from start to finish).
the problem isn't with sci-fi: it's with normal films that do stuff like that catapult scene in robin hood:prince of thieves. i wouldn't allow films 'one silly blunder' - if it's not sci-fi, it has to make sense, at least on it's own terms. if it is sci-fi, it needs to make sure it doesn't abuse the previlige with batcaves full of bat-garbage.
the perfect sci-fi film that i can't believe the article didn't take into account, is i reckon 'Prestige': it has exactly one piece of equipment that requires suspension of disbelief, due to it's impossibility. everything else in the film is human drama.
is it too much to ask that films are only allowed one transgression of the laws of statistics too? it's ok to have some mega-coincidence to set up the plot, but basing your plot around them is dispicable. and dickens, that includes you. it would mean action heroes would have to survive on their wits, not on their inexplicable luck. which would make george smiley a lot more deadly than james bond.