Detective Comics Volume 1 Issue 566

Grant Gordon had a poster in his childhood bedroom that depicted the cover of an issue of Detective Comics. The cover featured several characters, with the caption "prowl the Dark Knight's rogues gallery... if you dare!". (TV: The Return of Doctor Mysterio)

Behind the scenes
Although not explicitly identified in The Return of Doctor Mysterio, the issue shown was Detective Comics volume 1 issue 566.

Cover A of Doom's Day #1 was based on Detective Comics #566.