Ok, so as Brian pointed out, that wasn’t the right place to report this, so I’ll make sure I put this here, where it should, to not be ignored.
Nothing really major (and not a glitch either), but the sound the Mantaray makes at the end of the beam attack is taken straight from HL2. In HL2, it is usually heard when turning off Combine Thumpers.
In BM, the sound can be heard during a scene in STU where a Mantaray destroys a HECU tank. It instantly sent me to HL2 and thought about Combine, which is a problem. And beside, it’s way too mechanical for xenian biotech anyway.
Oh and just there, in case it’s not fixed yet, it’s possible to go through some rocks: https://forums.blackmesasource.com/index.php/Attachment/4859-Screenshot-20160605-192454-png/