One little suggestion
Since an error in a puzzle renders it unsolvable, isn't it kind of nonsense that we can only mark it for possible errors after we have solved it?
I understand that allowing players to do this before solving the puzzle will result in a number of false alarms from people who want to blame the puzzle for their own inability to solve it, but it just seems silly that the option of pointing out a possible error only appears after the puzzle is solved. We can see how few people actually bother to rank their puzzles. I'm sure the number of error alerts from players would be manageable for administrators to verify.