I saw it, and posted some comments that were lost in the server move.
I think it might be possible to make a historically accurate interesting movie taking place about 10,000 BC(E). This wasn't it. I can say that the time I spent watching it passed fairly quickly, even with the huge number of "that's wrong" moments. I regret to say that I didn't notice the zipper. I'm usually pretty fussy about things like that, and it escaped my notice altogether.

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Forming opinions as we speak