Have you noticed in watching a movie on TV show where a prop mysteriously appears, disappears, or moves from one scene to the next? Or someone's clothing changes between shots? Or it turns from day to night or vice versa from one shot to the next? Or there seems to be more food on the plate rather than less as the meal goes on? Or anything else like that?
I watched an episode of "Psych" Saturday night where Gus and Shawn were in Gus's car and Gus was driving. As the camera shifted from one to the other, I noticed the background looked the same, except it was moving in the opposite direction!