Similar to your #2, but less serious, I once wrote a script to power down virtual machines for a data center move. It was a nice piece of work too, grouping them in batches, sending shutdown commands to the guest OS, falling back to forcing a power off through the hypervisor after a configurable timeout...

I don't recall the specifics of the problem or the virtual infrastructure I was working with, but in short I didn't have sanity checks on what was being shut down. Ended up force shutting off the hypervisor/virtual infrastructure management system.

Added an extra few hours the move with that.