I bet I know what happened. Because you ordered an army to move that could move by land or by convoy, the system comes back and prompts with the by land or by convoy at the end. If you forgot to select this and save again, it reverted the order to a hold. I've had it happen to me and went "Doh!" and beat myself with a wet noodle for days for doing it.

@Maniac, I can guarantee that I ordered to move. I will start taking screenshots before orders, for safety's sake. How do I contact the mods?
@Draugnar, if you say so...There was only one infofield, though.

I think Draugnar's explanation is more likely.
Always double check your orders. Did they go from red to green after you saved? Close the browser/tab, then come back to the game screen to confirm that the orders were properly saved.

Yes, there is one when you first select it. But when it returns from the AJAX call, the second will appear if (and only if) that option is available.

I believe there was another thread on moves not reflecting orders. In short, moves not reflecting the orders stored onto the db before evaluation is literally impossible. If issues occur, they're only because the moves stored are not the moves intended. Typically, this is human error. It's easy to confuse territory names. It's likely that an AJAX call gets an http 500 because you clicked at a bad time for the server. This is a low probability even, but a possibility nonetheless. I think this is what happened in your case. You might have noticed the missing field, but that's probably harsh. Just bad luck, I think.

I wish there was warnings when your support and your moves don't make sense... like you supporting pie-mars, but pie-mars isn't a move. It would warn you to say "warning: you are supporting a move that you do not have entered: GoL S pie-mars, but pie hold"). So you can still order it, but the system analyzes and determines that it is a possible mistake on your part...

But sometimes you are supporting ally or even enemy moves and those warnings could give away a stab or allow you to deduce what your enemy's actual moves are.

@fortknox: Of course that would be impossible for if the support is going towards a foreign unit, but it would be nice for your own units. If I ever get a chance I wouldn't mind looking into it, but I hardly ever have free time these days.

They went from red to green, yes. And I ordered them several hours before the turn ended. Each time I went to check my diplomatic messages, I checked my orders.
*Sigh*
If there's nothing the mods can do (because of overload or fairness), I'll have to live with it...Too bad it denies me a build that was time crucial >.<

There is nothing the mods can do because reqinding the game would totally alter the outcome and it is unfair to just implement your order on your word alone.

rewinding, not reqinding

Have to say, I'd guess you're wrong.
As others have said, I just can't think of anyway that your orders could corrupt and yet end up legitimate. If there was an error then you'd expect it to leave an impossible order, not a different wrong order.

Another possible cause for your issue (although I think Draug may well be right) is that the precise save command didn't get through. Make sure to check your orders after saving.

I'll buy that. After the explanations above, I probably just had tired eyes and screwed up vision.
Thanks for the help everybody! I'll be sure to triple-check orders now!