Why it happens
- The hand was already wrong in the keyframe, and video generation amplifies it.
- The hand action is complex: gripping, pinching or interlacing with fine finger detail.
- The hand is tiny in frame or half-hidden, so the model has to guess.
How to fix it
Zoom in on every keyframe and count the fingers before approving it.
Simplify the hand action: resting, flat on a surface or a full-hand grip, not pinching, rubbing or gesturing.
When hand detail matters, shoot a dedicated hand close-up with a single action.
Frame hands out of shot or naturally behind a prop when they don't carry the story.
Use inpainting to fix only the hand instead of regenerating the whole image.
Before and after
Fails
She pinches the phone between two fingers and makes an OK sign with the other hand.
Works
She holds the phone in a full right-hand grip at chest height, left arm hanging naturally at her side.
Prevent it next time：Count fingers on every keyframe; no image with a bad hand goes on to video.
Worked examples