Why it can be confidently wrong, and how to head that off ahead of time.
Xiaoming has the AI's "15-day holiday" answer in hand and his suitcase packed when Xiaoting stops him: you'd act on an answer nobody checked?
The two of them act out how AI gets trained: first it reads huge amounts of text to learn how sentences continue, then it learns to follow instructions, and finally human feedback tunes it to be more useful and more honest. Along the way Xiaoming hauls in a giant stack of documents, the cafeteria menu included, and Manman gets buried under the paper. More material isn't always better. Find the few pages that matter first, then have it answer: that's the basic idea behind RAG. Even Xiaoting nearly grabs an outdated version.
You walk away with four quick checkups: ask about a chapter that doesn't exist and see if it makes one up; when you haven't given it any material, ask what its answer is based on; ask the same question five times and see how the answers shift; for exact math, have it write code and actually run it, then double-check with a calculator.