AI doesn't get 1 + 1 wrong anymore... but yes it can still be wrong. Most commonly if you ask it the wrong way. A calculator can do the same if you forget the parentheses, or mess them up slightly.
My feel is that the degree to which a wrongly inputed question can get a wrong answer is proportional to the complexity of the question you are trying to get an answer to. Kinda like computers made it possible for a simple mispelling of someone's name to have much more massive consequences than before computers.