Can be anything, from characters not using objects they have on them, to physics not being realistic, or a very big plot hole.
As an example, one of my friends told me that his pet peeve is that in a lot of sci-fi movies, when spaceships run out of fuel, they stop moving, while inertia and lack of atmosphere should keep them in motion.
The water in those sprinklers is disgusting too! It’s been sitting, stagnant in that pipe for years. It won’t be clear water like from the tap and it will stink.