“A plot hole is an implausible inconsistency that makes the audience suddenly wrinkle their collective brow and say, ‘Wait, that can’t be right,’ or ‘But why didn’t they just …?’

“If you’ve seen The Shawshank Redemption and wondered how the main character was able to reattach the Rita Hayworth poster to his cell wall after his escape; if you were left scratching your head at the fact that Harry Potter was the only one to notice Peter Pettigrew’s name on the Marauder’s Map; or if you wondered how anyone could have possibly known Charles Kane’s final word—’Rosebud’—when he, in fact, died alone, then you understand the frustration a plot hole can bring.”

Source: Editor’s Corner: Plot Holes: What They Are and How to Spot Them