Continuity mistake: After the dance, when Jack is talking to The Big Three, he grabs the towel and puts it on the other side of Rebecca. When the scene cuts back to Jack rubbing Rebecca's belly, the towel is still on Jack. Then, when Rebecca's water breaks, it is back to being on the other side of her. (00:03:40 - 00:04:12)
Factual error: Pierre Bezukhov's spectacles are of the type with nose pads, which were not invented until the late 1920's.