As the plot featured a doppelganger of Patrick McGoohan's Number Six character, McGoohan's stunt double Frank Maher has a lot of screen time alongside the "real" Number Six.
Unlike all the other residents of the Village, Alison is referred to by her name rather than by number.
With Earl Cameron's appearance as the Village's Supervisor in this episode, this makes "The Schizoid Man" the only episode to feature a black character, and a rare TV episode at the time to feature a black character in a role of authority.
This is the only episode in which the large white balloon who acts as the Village guard is named on-screen: "Rover".
Per the title, the Schizoid personality disorder (SPD) is a personality disorder characterized by a lack of interest in social relationships, a tendency towards a solitary lifestyle, secretiveness, and emotional coldness.