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)
Continuity mistake: Foggy and Karen enter Mrs. Cardenas' apartment. He stops at a break in the wall and turns to face her table. It then cuts to a close up as she's walking up behind him and suddenly Foggy has his head turned looking into another room. (00:28:49)
Continuity mistake: Matt is talking to Sgt. Brett who sets down a pen on his desk. After Brett starts to get up and lifts up his cup, the pen is still on his paper. When the camera cuts to an over the shoulder view from Brett, the pen vanishes. (00:21:53)
Continuity mistake: After the Madame Gao speaks to Fisk when he arrives, Fisk's mouth is hanging a little open. It cuts to a different angle after Wesley translates and suddenly his mouth is shut. (00:10:20)
Continuity mistake: After Matt and Claire kiss, she says she wondered when he would do that. In that shot, he has both of his hands up on her shoulders, and she is holding one of her own hands against her chest. It then cuts to a side view and now only he has one hand on her, further down her arm and her hand is down. (00:05:07)
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.