During the four-part crossover, Arrow will be celebrating it's 100th episode. A major milestone for any television series. There have been rumors of appearances by Robert Queen, Laurel Lance and Deathstroke. But they only get 42 minutes in the middle of a four part crossover to have an anniversary episode. Does it work? Executive Producer Marc Guggenheim told EW.com:
It feels like the 100th issue of a comic book, perhaps even more so than the 100th episode of a television show.
100th episodes of comics are usually oversized and contain major events like marriages or deaths. The Walking Dead #100 featured the death of Glenn. When reminded of that, Guggenheim said:
You know me, I always want everyone worried.