The Magic Sheet of Paper
Everyone remembers the scene where Jack draws Rose completely nude on a sketchpad. In fact, those who haven’t seen the movie even once know what we’re talking about. It’s that iconic of a scene! But what was also iconic was the mistake they made from one shot to the other.
In one shot, Leo draws a dark line from top to bottom. In the next, he shifts his hand to the left to continue the drawing, but the previous line is fainter than before. Unless he has a vanishing pencil, which hasn’t been invented yet, we’re chalking this up to shot splicing.