Science fiction movies don't tend to be quickly thrown together projects.
They often require a lot of supremely talented individuals coming together to tirelessly build a world that audiences can really believe in. However, even if that squad of gifted souls successfully manages to pull off this highly difficult feat, you can all but guarantee there will still be a few painful on-screen errors hiding in plain sight.
That isn't a knock on the filmmakers involved (everyone makes mistakes, folks!) but it is remarkable how often movies with astronomical budgets still let a number of tiny flaws seep through the cracks and onto the big screen for all the world to see.
It's highly unlikely that these ten sci-fi revelations will in any way effect how you feel about each of the movies included on this list, however, you will probably be left scratching your head at just how you managed to miss them staring you in the face for so long.
Don't blame yourself. You weren't on the lookout for grass on an asteroid, vanishing headphones, or phantom goat's legs. None of us were... until now.
10. Terminator 2: Judgement Day - Hand Switch
Arnold Schwarzenegger's entrance in James Cameron's Terminator sequel Judgement Day has become the stuff of movie legend... and rightfully so.
A completely naked T-800 enters a bar and demands a biker's 'clothes, boots and (his) motorcycle' . After the fool refuses the hulking figure, it decides to take them by force.
It's an absolute joy seeing Arnie swat away civilians with ease and its quite easy to get wrapped up in the compelling chaos going down in the scene. However, there is one moment which becomes slightly jarring as soon as you open your eyes to the mistake.
When the T-800 disarms one of the goons, the machine can be seen grabbing the guy's knife with his left hand and disabling him with his right. Yet, in the next shot, the robot is seen plunging the knife into his victims back using his right hand, with his left now being used to keep the poor lad on the pool table.
It's certainly an easily missed moment of dodgy continuity, but thankfully it takes nothing away from the no-nonsense arse kicking on show throughout this epic introduction.