From Zucchini Seeds Come..... Pumpkins????

This year we planted yellow summer squash, zucchini, and tomatoes. The tomatoes are doing great! The summer squash isn't doing very well, but we're hoping that it'll start growing better here soon. We're not sure what the problem is, but as soon as they're the size of a grape they fall off. The zucchini is HUGE!!! Well, actually, the zucchini aren't really zucchini. Somehow, our packet of zucchini seeds is growing pumpkins???? What do you think? Orange zucchini? or pumpkins???