On the DVD commentary to Batman: Gotham Knight (2008), Kevin Conroy said that this was one of his favorite episodes.
The dream reality in which Bruce finds himself mirrors Flashpoint, the alternate reality that Barry Allen created in the comics when he traveled back in time to prevent his mother's murder. Like Barry, Bruce finds that his parents are alive and someone else has taken on his superhero identity.
Aside from the similarities to For the Man Who Has Everything noted on the main page, the core plot of this episode was done in 1991's Detective Comics #633. The main difference is that the comic is pretty much a thriller all the way through, with none of the episode's psychological introspection.
At the end of "Beware the Grey Ghost", there is a poster of People Magazine. On the top of the poster there is a box that says "Matt Hagan: Man of a Million Faces". Matt Hagan becomes the villian, Clayface, (appears in Feat of Clay parts 1 and 2) who can change his physical appearence (as well as create objects such as axes or hammers from his hands). The People Magazine is dated October 19, 1992 which was the air date of the episode "Perchance to Dream". Additionally, the shadow of The Grey Ghost is Batman's shadow.