The title is a play on 'The Seven-Per-Cent Solution,' a popular book/movie about Sherlock Holmes.
The way Donald gets zapped by a security force field as part of a test pays homage to a similar thing happening to Scrooge in the episode "Armstrong (1987)" of the Original DuckTales (1987), when he was trying to get past a security force field placed by the titular robot of that episode of which had been trapping him and Gyro in Gyro's lab.
The song playing when Flintheart enters the funeral is "All I Do Is Win" by DJ Khaled and Mariah Carey (with Busta Rhymes, Nicki Minaj and P. Diddy). It's a rare instance of "real world" music being used on the series.
Gizmo Duck points out that Mark Beaks is live posting from "Crowchella," an in-universe version of the real Coachella.
The 87 in the episode's title is likely a reference to the year 1987, which was when the original DuckTales (1987) series premiered.