Logical inconsistency in the story—something happens without explanation or contradicts established rules. Script flaw audiences catch immediately.
A plot hole arises when the narrative story collapses in on itself — not dramatically, but logically. The viewer sits there thinking, "Wait, that doesn't make sense." This is not the same as a deliberately open question or a mystery. A plot hole is a flaw in the screenplay that the writer overlooked and which destroys the credibility of the world.
In practice, you recognize it immediately when reading or during editing. Character A is in the car in Scene 1, Scene 2 begins 20 seconds later — but the person is suddenly at the other end of town without explained transport. Or: The rule of the world states that magic only works in moonlight, but in Scene 47, it's used at noon without being addressed. This isn't a narrative risk, it's sloppy. You can partially salvage it during shooting (quickly shoot a transition scene, a line of dialogue), but often you notice it too late.
The danger is: plot holes are cumulatively toxic. One mistake? Viewers will forgive you. Three to four? Emotional engagement drops rapidly. Most mistakes happen during the telling of the exposition — that's where rules are established that must apply later. Or in the resolution, when a solution is hastily written under time pressure that is not compatible with the established rule set.
From the set, you can do little about it, but as a cinematographer or editor: you see inconsistencies immediately. A character wears the blue jacket in Take 1, red in Take 2 — that's continuity, not the same as a plot hole, but it signals a lack of control. If you notice during shooting that a scene-to-scene logic breaks, address it. The editor can't perform miracles later.
This differs from an unanswered question (deliberately mysterious) or a deus ex machina (unsatisfying solution, but logically consistent). A plot hole is a breach of one's own game rules — and the viewer in the third row notices it immediately.