Glory: Watching Your Wrist
There are more time travelers in period pieces are more common than you think. A perfect example is the 1989 film Glory. In this film, there is one of the civil war soldiers that is showing off some futuristic gear. In one specific scene, a foreground extra is wearing a wristwatch. Not only that, but it is also a digital watch. The actor should have removed his watch before reporting to set or at the very least someone should have caught this oddity.