Back To The Future 3 - Clara's Vanishing Gloves
When Clara is on the train to leave town, she pulls a cord to cause an emergency stop. During this scene, her hands are covered by brown leather gloves. She jumps off the train and begins running. In the following shot, she is running towards the camera, and her hands are no longer gloved. It would have been impossible for her to take them off that fast, and throughout the remaining parts of the film's climax, the same gloves are seen on her hands.
The movie on any format (slow motion may help).