Jennifer Hudson's son made his movie debut by accident.

The singer-and-actress' little boy David, four, ''snuck into shot'' when she was filming 'Black Nativity' and so is visible in the finished film, though the youngster was disappointed not to have a bigger part.

She said: ''He kind of snuck into the shot and ended up just sitting there, and the camera was rolling, and it's like now you can't move, now you're on the clock.

''He saw the movie and he's like, 'That's it? Where's the rest of my shots?' ''

Jennifer also admitted David struggled to understand how Jacob Latimore could play her screen son.

She told the New York Post newspaper: ''He doesn't get the concept of me having another son in the film. He'll say, 'No, mommy, I'm your son. That's not your son.' He's only four so he's still trying to grasp all that.''

And though David - whose father is Jennifer's wrestler fiance David Otunga Snr. - would like to be on television in the future, he has another ambition.

She explained: ''He wants to be a superhero.''