Most Financially Damaging On-Set Mistake for Indie Post-Production?

Hey everyone, I'm an AD working on a micro-budget indie feature right now. We shot on an ALEXA Mini with some vintage glass, and honestly, every department is stretched thin. I’m thinking ahead to post and trying to anticipate potential landmines. You always hear about how crucial clean plates or thorough reference photos are for VFX, or consistent sound recording for audio, but when it comes to indie budgets, which single on-set error typically causes the most financially devastating ripple effect in post? I'm not talking about minor fixes, but the kind of mistake that blows a good chunk of the post-production budget. We're trying to be as diligent as possible, but knowing where to put our truly limited resources would be a huge help. What's the biggest money pit you've seen caused by an on-set oversight?