Because a language model predicts plausible text rather than verifying truth, it can invent citations, APIs, or facts — especially for niche, recent, or under-represented topics. For production systems this is a primary reliability risk.
Mitigations all aim to ground or check the output: retrieval-augmented generation with citations, output validation and guardrails, and systematic evaluation. Open-source tooling exists for each, and no single fix eliminates the problem entirely.