This isn't exactly a blooper, but in the movie Immortals, Theseus, our demigod hero known for fighting the Minotaur, gets his hand on the Epirus bow which does not need any physical arrows. Instead it generates magic missiles which unerringly hit their targets with uncanny precision and accuracy. The bow is magical, so it can do things which ordinary bows cannot do, such as generate arrows as needed and defy the laws of physics. it's not supposed to work like a real bow.
In one scene where there are hostages, Theseus lets loose several shots, one after the other, but they all hit at the same time. If actual real-world arrows were released one after the other, they'd hit one at a time and never all at once.
This isn't exactly a blooper since the arrows are supposed to be magical. But then if these arrows can accelerate magically, it makes one wonder why they should have to take so long to hit the mark. Why not get there in no time at all? I'm sure there's some magical explanation, but even without one, great special effects and the power of imagination and creativity can do wonders to suspend disbelief at the movies.
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