The 32-year-old Oscar winner's son got filmed accidentally when she was shooting and was perfectly visible in the finished film, reported Femalefirst.
"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," Hudson said.
"He saw the movie and he's like, 'That's it? Where's the rest of my shots?'," she added.
The actress said David is still struggling to understand how someone could play her son on screen.