The original Broadway production of and source for the screen play "Dulcy" by George S. Kaufman and Marc Connelly opened at the Frazee Theatre on August 13, 1921 and ran for 241 performances. The play had been made into a film once before as Dulcy in a 1923 silent version starring Constance Talmadge in the title role.
About 40 minutes in, when Donald Ogden Stewart is at the piano, he plays a little snippet of "Singin' in the Rain," which had been introduced the previous year by Cliff Edwards and the Brox Sisters in MGM's "Hollywood Revue of 1929." The studio would use it several more times over the years, most famously in the 1952 film of the same title.
According to the October 26, 1929 edition of Exhibitors Herald-World, the opening driving scenes were filmed near Pasadena, CA. An eight-cylinder car was required, since it was discovered using a six-cylinder one caused interference with the sound recording. The "engine explosions" were "out of time with the high sound-wave frequency of the microphone." A platform was built over the front bumper where cameras and microphones were mounted, then cables were run to a sound recording truck that drove ahead. Elliott Nugent had to maintain a speed of 20 mph in his car to keep the pace even with the sound truck.
Not So Dumb was the third and final film collaboration that Marion Davies made with director King Vidor. He had previously directed her in the 1928 silent comedies The Patsy and Show People. While William Randolph Hearst preferred to see Davies in serious roles, Vidor was successful in bringing out her natural talent for comedy and showcased the actress at her best.
This film fared poorly at the box office, resulting in a loss to MGM of $39,000 ($708,000 in 2022) according to studio records but it was favored by critics. A published review deemed Not So Dumb a "first-rate comedy brightly done," declaring that Marion Davies "proves conclusively that she is a comedienne." The Jun 1930 Picture Play also praised Davies, stating: "Her work is so clever you want to choke her while laughing at her dumb efforts to be the little fixer between her fiancé and his boss."