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.
Shock waves need a medium to travel. If something explodes in space, it will send debris that might hit you, but if it produces a shock wave in a low-density environment, it would probably miss you due to the lack of matter.
Ah thanks, til that shockwaves aren’t distortions of space-time itself and just a pressure wave on whatever is in the area.