Sci-fi movies often dazzle and amaze audiences with imaginative interpretations of the future, mind-blowing visuals, and spooky, physics-bending twists -- but there's little to celebrate about the genre's onscreen mistakes. Or is there?

From a glaring date blunder in "Back to the Future" to a blatant continuity error in "Alien," here are a few movie mistakes from sci-fi classics.

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