Visible crew/equipment: Wesley enters Vladimir's office to talk with him and Vladimir had a large white window behind him. As they talk, the reflection of a green screen of these windows is in Wesley's glasses. (00:06:34)
The Dark at the End of the Tunnel - S2-E12
Visible crew/equipment: When Frank closes the door to the shed, you can see a crew member in the trees to the right swaying left to right as if he were looking for something. (00:45:15)
Visible crew/equipment: A random hand appears on the left side of the screen when Matt is punching Fisk. (00:33:59)
Chosen answer: After some research, I can say that no, Cass is not a character of Marvel, nor is he present in the Netflix show. As far as I can tell, it's either a real person, or a random name chosen for the coffin, most likely the former. In another season of Daredevil, the show utilized a real cemetery displaying real names in the tombstones.