How did Emily escape in movie Case 39?

How did Emily escape out of the car which was immersed in water in the end? Is it even possible to open the door of a car which is already deep into the water and why was the Demon not able to escape the same way?

I mean it seemed really powerful or was it just that the Demon was only doing everything at psychological level...?

plot-explanation case-39

Best Answer

As to how she opened the door, the simplest explanation is that this is a little bit of filmmaker's license. It's certainly possible to open a car door underwater if you let the car fill with water and it's theoretically possible to hold your breath long enough to do so.

As to why the demon couldn't escape the same way, Emily was able to hold it underwater for a full twenty seconds longer than she herself was submerged. It then grew to gargantuan size (in order to punch out of the car rear light) but seems to have gotten itself stuck into the structure of the car.