Re-watched Godzilla (2014) recently and a question occurred to me: Are there any regulations about shooting at something against which your weapons would be completely ineffective?
The scene that stuck out as particularly egregious in that specific movie was the first time he made land-fall and the soldiers nearby opened fire from a rooftop over a crowd of civilians. But you see this kind of thing all the time. Bullets bouncing off of a target that may or may not even be engaged with the soldiers shooting at it...