10 Things You Didn't Know About Cape Fear
4. De Niro And Lewis Improvised The Kiss Scene
Being warned by the director that De Niro was going to improvise during their take of the uneasy kiss scene, Lewis didn't know what to expect when it came to capturing the seduction of her underage character. After sticking his thumb in her mouth a couple of times, Lewis got the gist however, and expertly reacted to create a truly uncomfortable and affecting scene with De Niro.
Setting up two cameras and letting them roll on each actor, the scene was only filmed three times total. It was the first take that ended up making it in to the movie. Lewis described the moment in an interview, stating she was warned by Scorsese with "'Bob is going to do something.' But he wouldn't say what. I'm sure they didn't know how I was going to react, if I would stay in the scene or lose it."