First-Time Producer Pitfalls: Beyond the Obvious?

Hey everyone, I'm usually on the other side of things as a Script Supervisor, making sure shots actually match and keeping track of the script. But I'm dipping my toes into producing a short film with a couple of friends, and it's a whole new ballgame. We’re trying to build a solid budget, and while we've got a decent handle on equipment rentals and crew rates, I'm starting to get nervous about all the 'hidden' costs. Things like fringe benefits for crew, or exactly how much we'll need for sound design and color grading in post. We also haven't really factored in a marketing budget yet, which feels like a huge miss. For those of you who've produced before, especially as a first-timer, what are the most common or dangerous financial blind spots you've encountered that people often completely overlook?