Implicit agreement between film and audience: the viewer accepts the fictional world as long as its internal logic holds. Break the logic, break the contract.
The viewer enters the cinema with a tacit agreement: they will accept the artificiality if you give them a consistent world in return. This is the suspension of disbelief—and it is more fragile than one might think. Not because people are naive, but because our brains are constantly searching for internal logic. As soon as this breaks, we're out. The illusion doesn't collapse because something is unrealistic—it collapses because something is inconsistent.
On set and in editing, this means specifically: a fantasy world with magic is absolutely legitimate. A superhero who flies—no problem. But if this hero suddenly loses their powers without explanation, or a character has a conversation we just saw, even though they weren't there—then, as a viewer, you unconsciously ask yourself: Why should I still trust this film? That is the break. Viewers forgive you fantasy. They forgive you bad effects, bad locations, even budget gaps—as long as the internal logic holds. What they don't forgive: arbitrariness.
This has massive practical consequences during shooting. If a character has a phobia in the first act, they can't suddenly be brave in the third act without us understanding the journey. If a gun has ten bullets, it can't fire twenty times. If it's day when the sun is rising—not when it's setting. These details seem small, but they are the foundation. The best direction, the best editing, the best music—all of this only works if the viewer is still invested. And investment ends when the contract breaks.
This becomes particularly critical in long formats or with complex plots. A series over eight seasons must consistently adhere to its rules—any inconsistency will be torn apart in forums. For blockbusters with dozens of plotlines, you need script supervisors who keep an overview. But even small indies live or die by whether the viewer follows the rules. The suspension of disbelief is less a question of size or budget than of attention and respect for the world being told—towards the audience and towards your own film.