The ending of the Gospel of Mark containing the handling of snakes was added by later scribes and was not part of the original text.

“I was just making stuff up here. So, I mean, who put that in there? Uh, later scribes. You know, as I was telling you, we don't have the original of Mark. And one of the big things they did with Mark is they added 12 verses after Jesus' resurrection, the scribes did”