I think most movies use the Chinese Type 56 assault rifle, which is a Kalashnikov knock-off and is far more common in the US than the real thing. Most people can't tell the difference between the two.
BTW, I highly recommend "The Gun" by C.J. Chivers. It's a fascinating historical treatise about this weapon.
Actually the Chinese copies are considered pretty good, but are pretty rare because the US embargoes "assault" weapons from there for civilian use with State Dept's permission (never).
Most of the cheap ones in the 90's were Maadi (Egyptian), and now they're usually Romanian.
Yeah, pretty much. It's an extremely simple (albeit clever) design so there's only so much you can get wrong when you're copying it. Note that the Type 56 like most other AK knock-offs are really copies of the later AKM "improved" model, which was cheaper to manufacture. So comparing it to the original AK-47 is probably not fair. Then again there aren't many copies of the original model around anymore.
In the books, a near future (near our present) naval task force accidentally travels back in time to WWII. The U.S. eager to get a leg up in the war asks the chrononauts to give them future tech. The only problem is that WWII American doesn't have the manufacturing technology to produce any of the current equipment. So the chrononauts dig through their archives and find plans for the AK-47, which, as it turns out, is manufacturable in early 1940's U.S. thereby giving the Americans a weapon from the future, but still old enough that they could be produced in bulk.
BTW, I highly recommend "The Gun" by C.J. Chivers. It's a fascinating historical treatise about this weapon.