When Jed first descends the stairs into his 'lair', the characters displayed on the monitor screens are The Psycho-Pirate and Captain Cold, both members of the Rogues Gallery of the Flash in the Silver Age of DC comics, as is The Pied Piper, whom Jed's "Sandman" sets off to confront. Jed mentions Johnny Sorrow, the Phantom of the Fair, and Dr. Death, who are all villainous opponent of various incarnation of Sandman or his ward Sandy.
The red and gold costume donned by Jed is a comics-accurate rendition of garb worn by the Bronze Age hero Sandman. He was created by Jack Kirby in the for a brief run from 1974 to 1976, wearing the costume seen in Jed's dream.
Barbie and Ken say they are meeting their friend Sindy. Sindy was a fashion doll created in the UK as a rival to Barbie.
During one moment in Rose's travel through his friend's dreams one of the posters of Jed can be seen, but with all its letters scrambled, making it impossible to read. This could be a reference to the idea that in dreams we can't read because reading is a function of the right side of the brain and dreaming is a function of the left side, therefore both action could be impossible to perform at the same time.
Keen-eyed viewers may recognize Martin Tenbones (voiced by Lenny Henry), who could be glimpsed in the first episode "Sleep of the Just" at the 1:44 mark, aboard a triple masted sailing vessel gliding beneath the bridge to Dream's castle.