The evidence board has a picture of the pistol that was used to kill Cash. It is incorrectly identified as a Glock. As the pistol has a lot of third party modifications it is hard to tell what model it is for certain, however it appears to be a Heckler & Koch HK.
In the opening scene, an art class is about to begin sketching a nude male model. The model hasn't removed his towel yet, but it's clear that he's wearing black underwear beneath the towel. Why would a nude model wear underwear? Nude models wear robes, towels, or other loose clothing because tight clothing like underwear and bras can leave marks on the skin.