One-Page Pitch Pitfalls: Beyond Typos, What's the Core Conceptual Error?

Hey everyone,

I'm Isla, a costume designer usually more focused on fabrics than financing, but I'm slowly dipping my toes into producing a short film concept I'm really passionate about. It's a period piece, so definitely not a low-budget walk in the park! I've been researching everything about pitching, especially the dreaded one-pager, since everyone says it's your 'most important document.'

I understand the basics (clarity, conciseness, no typos) but I keep wondering about a deeper issue. From your experience, especially those who review these regularly, what's a conceptual mistake you consistently see emerging filmmakers make on their one-page pitch that instantly makes a project seem less viable? Beyond just superficial errors, what's a fundamental misunderstanding or misrepresentation that truly undermines its potential in your eyes?