Despite massive advancements in Retrieval-Augmented Generation (RAG) and semantic claim matching, language models continue to generate factually incorrect information. This comprehensive 2026 guide explores the profound technical flaws behind AI misinformation—from context window degradation to the limitations of semantic entailment—and details how enterprises must utilize Generative Engine Optimization (GEO) to secure verifiable, hallucination-free visibility in AI search platforms.