When you build a relationship with your audience in a film or on TV you lay a foundation. That foundation is like an understanding between you and them about the type of story you are going to tell. If you want to keep that relationship you have to make sure you follow the rules you have set.
If you do a good job of playing with your own set of rules the audience will go along with what ever story you are telling. If you break those rules you also break that foundation and in turn the relationship with the audience. I am going the long way to describe the suspension of disbelief.
to give you an example I am going to explain why I am not watching Fox's Sleepy Hollow anymore.
I understand this is going to be a world where magic is real and the headless horseman is one of the four horseman and is trying to bring on the apocalypse. So I am bought into the whole I am going to see things that I won't normally believe because you have given me the frame work of magic to explain it. Let me Just hang my disbelief on this plot hook. So I understand the physics to be real with the possibility of being enhanced by magic.
During season one they had laid that out for me. I am with them for the season cliff hanger. The main character Ichabod is buried alive. He is in a poorly made coffin so the dirt that he is covered with is falling through the crack in the wood. He detects the presence of sulfur so he quickly takes a scrap of cloth and rubs it in the sulfur and the lights it. A spectacular explosion and the six feet of dirt that was on him is now blown completely free.
Nope, you lost me.
See the problems I have with this can be summed up in three points. First and foremost is the fact that sulfur is not explosive by its self. It is one component of three that is needed to make black powder. Now you can ignite and explode sulfur if you make it into a fine powder and let it fly in the air. But as our hero was under packed earth there was no way that it could do that.
Let say for the sake of argument you can do that, he would have the force of that blast coming down onto him just as hard as it would have onto the pact earth above him. The force of the blast would have crushed him.
Now lets say that the force didn't kill him, that would not have been enough force to clear the dirt completely away from the grave, it would have blown the dirt into the air and then it would have come back down again crushing him without the benefit of the coffin that he just blew away.
I know this next line is going to sound completely foolish but here it goes. You have to make your make believe magic enhanced world believable.
There are other problems with the show. In consistencies with the day and night transitions. Its noon and the characters say they have to get across town and now its night, I mean how big is this little town?
Also the way that Ichabod has a photographic memory but cant seem to keep names straight.
A word to the story tellers out there, when you gain the trust of someone and they join you on the journey you start, keep them engaged by playing by the rules. What ever you make them to be.