On July 21, 1936, the Los Angeles Evening Citizen News (aka Hollywood Citizen-News) listed RKO films in production or preparation, including "The Riddle of the Dangling Pearl," based on a Stuart Palmer novella. James Gleason and Helen Broderick were indicated as the principal actors. They had appeared in RKO's previous Hildegarde Withers production, Murder on a Bridle Path (1936). However, on Aug. 17, the paper reported that Broderick would not be appearing in the film, as she had too many other assignments. (She appeared in five RKO releases in 1936.) The article indicated that James Gleason's wife Lucille was negotiating to take over the role of Hildegarde Withers, but on Sept. 4 an L.A. Times story indicated that James would be teamed with Zasu Pitts for the film, which was released in December as The Plot Thickens (1936).
John Carter (Richard Tucker) drives a revolutionary new 1937 Cord 812 roadster, owned by RKO and used in several other of their productions, such as Super-Sleuth (1937), in which it's driven by Jack Oakie as film star Willard (Bill) Martin. As usual, the police drive a more traditional and more conventional 1936 Ford sedan.
In the previous series entry Murder on a Bridle Path (1936) Louise Latimer and Owen Davis Jr. play Barbara Foley and Eddie Fay, a couple hoping to elope. In this episode they reappear, and although Hildegarde recognizes them, their names have inexplicably changed to Alice Stevens and Robert Wilkins.
The fifth of six films in the Hildegarde Withers - Oscar Piper series released from 1932 to 1937.