Lord of The Rings: Fellowship of The Ring - The Magical Switching Hobbits
When The Hobbits are attacked on Weathertop by the Ringwraiths. Look closely as they try to comfort Frodo after he has been stabbed by the Witch King. In one frame, Pippin is sitting by Frodo's side and has his hand on his forehead. In the next shot, however, it seems as though Merry and Pippin have magically switched places. Now, Merry is at Frodo's forehead and Pippin is on the other side next to Sam.
A Fellowship Of The Ring DVD (preferrbly widescreen)