Seventh of fifteen films in the "Philo Vance" series released from 1929 to 1947 that began with The Canary Murder Case (1929). The novels by S.S. Van Dine were extremely popular and studios bade for the film rights to each one, making the author very wealthy.
This film went through many casting changes before production began. MGM originally planned this as a vehicle for William Powell and Myrna Loy, but Powell refused, saying he was tired of playing the character. The studio then considered Otto Kruger, Fred Keating, Warren William, and Ricardo Cortez before settling on Paul Lukas two weeks before the production started. Eugene Pallette and Edward Brophy were slated for the role of Sgt. Heath that eventually went to Ted Healy. Constance Collier was set to play Mrs. Llewellyn, but she backed out to take a break, so Alison Skipworth was borrowed from Paramount for the role.
Gene Perry as French Waiter, William Worthington as First Bidder, and Edward Van Sloan are in studio records/casting call lists as cast members, but they did not appear or were not identifiable in the movie.
When Vance is outside the heavy water plant and they are scurrying to get in out of the rain, the music changes to Les Preludes by Franz Liszt, which was later used as the theme music for Flash Gordon Conquers the Universe (1940).
Note that Philo Vance encounters an employee at the auction - played by Jay Eaton - who looks remarkably like William Powell, who had played Vance in four previous pictures.