As Jack Ryder busts into the clothing store to redress himself, a sign above the boutique reads "Ditko's Vintage Clothing", named after Steve Ditko, the creator of The Creeper. A mannequin of The Question, another of Steve Ditko's characters, is seen in the background as a mannequin.
The dramatized Batman in Jack Ryder's special report, "Joker: The Madness Behind the Laughter", looks similar to Robert Lowery's portrayal of Batman in the serial film, Batman and Robin (1949), as well as Batman in his very first appearance in "Detective Comics" #27 as illustrated by Bob Kane.
When Jack Ryder is discussing the Joker's history in his special report, he mentions the Joker's time working with Salvatore Valestra and the camera cuts to a photograph of the Joker before the Axis chemicals accident. This was the photograph Batman found in Salvatore Valestra's home during the events of Batman: Mask of the Phantasm (1993).
The Joker's three henchman are drawn and voiced to sound like Larry Fine, Moe Howard, and Curly Howard, the Three Stooges.
Bruce Timm has stated in an interview that the Creeper is basically what he envisioned for his original concept of the titular character of Freakazoid! (1995).