Star Wars Episode 2: Attack of the Clones - Anakin's Missing Arm
After Padme and the clone soldiers arrive right after Doku has left. Watch Anakin's arm when Padme and him hug at the end of the scene. You can see the blue on his arm (so editors can make his arm disappear) as it passes by his body. Although hidden in shadow you can definitely see the blue screen.
the movie and maybe slow motion if you can't see it the first time