At first in E2L1 when you use the switch in the broken elevator the sound of the second switch opening is played two times
The second bug I found is in E4L1 when you enter in the room protect by energy doors (with blue pass but I'm not sure of the color, I'm visual impaired) there's a secret that you can access by use on the two computers but there's a switch textures on the screen (there's a window broken sound when you kick the switch)
See you soon

the doc sataper