Filing a patent application is a complex process, and even small errors can have devastating consequences — from rejected applications to lost intellectual property rights. At Moran IP Law Firm, we have seen inventors lose patent protection due to easily avoidable mistakes. This article reveals the five most common patent filing errors: insufficient prior art searches, overly narrow claim drafting, premature public disclosure, missed deadlines, and failing to consider international protection. For each mistake, we explain why it happens, what it costs, and exactly how to avoid it. Whether you are a first-time inventor or a seasoned R&D professional, these insights could mean the difference between securing your invention and losing it entirely.