The whole "they left the green card in my passport" story comes up every now and then. People think it's a big drama, but in reality the US does a terrible job tracking visitor movements.
In any case, if you stayed in the US for two weeks only, and left just a few days ago, you could still legally be in the US. That means that you'll be sending the I-94 in before its expiration date -- no need to get statements from embassy personnel. Do not keep the I-94 in your passport, and it is very likely that nobody will even mention it. Even if you had turned in, it wouldn't be processed yet.