Continuity needs work - writing tip

A former student e-mails: I received a comment in a critique that the "continuity needs work." What does that mean in terms of a short story? I can't see anything I did wrong, but don't want to argue.

Answer: In simple terms, continuity is not getting the horse behind the cart. People shouldn't arrive at their destination before they leave. If someone answers the phone, it should ring first, not after it is answered. If someone lights a cigarette, they should put it out before they light another. No one should go upstairs when they already ARE upstairs. Don’t laugh, I’ve seen all of those happen, and in published work, too!