Rogen, Streisand explain chemistry

Seth Rogen and Barbra Streisand in "The Guilt Trip."

Seth Rogen and Barbra Streisand in "The Guilt Trip."


, Last Updated: 9:06 AM ET

BEVERLY HILLS -- At one point in The Guilt Trip -- a comedy in which Seth Rogen plays an inventor who brings his mom, Barbra Streisand, along on a cross-country road trip -- the most unexpected thing happens.

Rogen and Streisand are sitting in a car clearly improvising their scene -- and it proves to be the first of several unscripted sequences.

Improvisation? That's par for the course where Rogen's concerned, but Streisand? A self-admitted perfectionist whose micro-managing pursuit of excellence is the stuff of legend? Improvising?

Could it be that Rogen, who, at age 30 is a full 40 years younger than his iconic co-star, has managed to loosen Streisand up?