I don't even think it's so much a matter of knowing the ground rules, as it is a matter of, unless it is clearly a homerun you run the bases as though it isn't until you see the umpire signal homerun. (And there isn't any signal for "in play". So if the umpire makes no signal, assume it's in play.)
Exaclty my sentiments yesterday when it happened. This is more of a "head up the ass" moment.
