WARNING - This article contains SPOILERS for the "Subject 9" episode of The Flash.
An Easter egg in "Subject 9" - the latest episode of The Flash - makes reference to the very first battle fought by the Justice League of America in their first comic book appearance. The reference was hidden among the blog entries on the website of Izzy Bowin - an aspiring country western musician, whom the episode revealed as The Arrowverse equivalent of the classic comic-book villain The Fiddler.
Season 4 of The Flash has centered upon the battle between Team Flash and Clifford DeVoe - a.k.a. The Thinker. A super-genius whose intelligence was enhanced even further through the use of a special "thinking cap", DeVoe facilitated the creation of 12 metahumans, whose powers he has been systematically stealing as part of his grand design. Izzy Bowin, who developed the power to manipulate sound waves, was DeVoe's next target and Team Flash was having difficulty in tracking her down until PI Ralph Dibny suggested the obvious solution - check out her social media.
Izzy Bowin's blog revealed that she was still in Central City, picking up copies of her new single from a local sound studio. It also revealed that she recently had to cancel her concert in Blue Valley due to "some sorta starfish situation." That in and of itself sounds awfully unusual, but comic history buffs recognized this as a clear reference to Starro The Conqueror - a giant, telepathic alien starfish who has attempted to conquer the Earth on several occasions.... twice by using the town of Blue Valley as a staging ground!
The Justice League of America first faced Starro The Conqueror in The Brave And The Bold #20, first published on December 29, 1959. An updated version of this story was told nearly 40 years later in JLA Secret Files #1 (September 1997), with The Flash alerting the Justice League to a swarm of starfish-like creatures that attached themselves to people's heads (much like the face-huggers from the Alien movies) and took control of their minds. The Justice League faced these aliens again one year later in JLA #22 (September 1998), where writer Grant Morrison developed them into a more Lovecraftian menace that sought to attack humanity from the realm of dreams. This led to half the Justice League joining with Dream of The Endless to fight Starro in a boy's dream while the rest of the team fought the prime Starro on the material plane.
The sequence with Izzy Bowin's blog offered up another Easter Egg for eagle-eyed fans. Her touring schedule dropped the names of several cities that will be familiar to fans of DC Comics and the Arrowverse, including Green Arrow's hometown of Star City, Hal Jordan's hometown of Coast City, and Bludhaven - the adopted protectorate of Nightwing. Sadly, it seems unlikely we'll get to see Team Arrow or Team Flash face down telepathic alien starfish anytime soon.
The Flash returns on Tuesday, March 6, with "Enter Flashtime".