It's no secret: filming a period movie is tough... really tough. A filmmaker's biggest challenge, of course, is taking a modern city and turning back the clock.

Successfully disguising a location to make the audience believe they've actually stepped back in time is no small feat. It requires countless antique props and (very) vintage clothing, and the need to hide all things present day!

Regardless of whether or not the film has successfully transported us back to a different era, there's usually a mistake or two that slips through the cracks. From "The Godfather" to "Pride & Prejudice," here are a few "oops" moments from your favorite period pieces.

As always, photos are courtesy of MovieMistakes.com.