If you missed the update added to the meta 4/4 post earlier today, here's the Coles Notes version:
I made a small but significant oversight when constructing puzzle #4, and didn't catch it in time. So today was pretty agonizing, as I was stuck at work knowing that the puzzle was flawed (but easily fixable), yet unable to do anything about it. The upshot is that I've had all day to dwell on it and figure out the best way to handle this awkward situation. My initial reaction was to repost the puzzle with the mistake corrected, but, since a number of visitors had already solved the puzzle and submitted answers, doing that would mean that solvers are competing for the same prize but solving different puzzles. I can't have that, so I'll just have to suck it up and accept that it's a flawed meta.
However, things could be worse: a few solvers have already submitted the correct answer (and have proven that they fully comprehended why it's the correct answer), so, flawed as it is, the meta is still demonstrably solvable. Because of that fact, I'm going to leave the puzzle as is and continue on like normal, with one exception:
If, once you see the solution and the error that I made (to be posted Sunday night, after the contest closes), you truly believe that you would have gotten the answer but for the error, send me an e-mail to let me know. I'll trust you and count your solution as correct. If it messes up the proper selection of a sole winner, I'll compensate with additional prizes.
Sound reasonable? If you have a better idea to make it fair, let me know.