Mason jars? Didja put lids on them loosely? If so, you're probably OK. Otherwise, chances are pretty good you've got an acetobacter colony going to some degree. If it still tastes OK, you can probably salvage a drinkable cider by pasteurizing 'em and sealing 'em up. (Put a lid on really tight, stick jar in canner, bring to boil for 60 seconds, pull jars out and put on towels. Don't forget the "really tight" part -- alcohol boils off at 170 degrees if you let it.)
I've never tried it but I can't see why you couldn't use a not-too-tightly-screwed-down two-piece mason jar lid as an airlock for cider. It wouldn't be a hermetic seal, but pretty close to it, letting gas out and nothing back in. Anybody ever tried this?