In Season 4 "Luther Gillis: File #521" (1983), Tanaka referred to Biff as his grandson. However, in this episode, Biff is Tanaka's nephew.
In the beginning of the show the police discuss the Watergate Hearings and "The Rockford Files" both being on TV the night before. The hearings preceded Nixon's August, 1974 resignation; Rockford's first season started in September, 1974. The episode discussed is one of two featuring Tom Selleck as Lance White, but those episodes ran in 1978 and 1979.
In "Pleasure Principle", the character played by Amy Yasbeck is listed in the closing credits as Diane. In this episode and in "Resolutions", she is listed as Diana.