One thing I have noticed messed up in a lot of fiction (written/tv/movies/etc) is how loud guns actually are. Scenes of multiple people without any hearing protection emptying their guns that doesn't have any kind of supressors/silencer multiple times in a closed space (usually a single room) and then just casually chatting with each 5 seconds later.

In general the sounds of guns are very bad in most movies/tv shows (Heat from 1995 comes closest for me).

The only time movies try for sound accuracy is with flashbangs.

Michael Mann movies tend to get this right, Heat and collateral have really decent gun sounds. Turns out they are very loud.

Edit: just noticed you mentioned heat already, I need more coffee…

I wonder if part of this is also failing to consider the acoustic effect of loud sounds in enclosed spaces. Guns don’t sound nearly as loud if you only shoot outside.