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.
Oh man, the Disney Star Wars Trilogy is full of these.
I get that Star Wars movies are effectively a fantasy adventure series in Sci-Fi clothing, I’m not expecting perfect logical sense out of everything, but internal consistency has absolutely not been Disney Wars’s strong suit.