This is a good example of what Chion talked about when he coined “anempathetic”. Anempathetic music is often diegetic, meaning that it’s coming from inside the movie’s action, rather than being exterior to it. The example that’s usually given is a radio or record playing in the background.
“Causal” refers to the actual source of a sound. You see a gun go off and you hear a bang, that’s a causal relationship. In your example, the contrast is semantic: it’s the meanings that the visuals and music convey that are in contradiction. For an example of causal contradiction used for comic effect, look at around 2:10 into Duck Amuck.