I think the point they are getting at, if I understand the commenter correctly (and assuming the wording of the article is accurate), is that someone on the line had the ability to make a change to the production process without authorization.
That would not just be a "production line mistake", instead it is indicative of a serious policy and procedure failure. No single person on the production line should have the ability to make unauthorized changes to the procedures being used in production.
I hate analogies, but to use yours, it is a rogue employee that was able to change critical code with no approval process -- and no one else noticed that code was being changed and went ahead with shipping it out.