During Constantine's run on NBC, Emmett J. Scanlan (Krypton) appeared as Jim Corrigan/Spectre. However, during the CW's "Crisis on Infinite Earths" event, the character was played by Stephen Lobo (Afghan Luke). Showrunner Marc Guggenheim has confirmed a piece of dialogue in that scene was indeed a nod to John Constantine's solo series.The scene in question sees Constantine, Mia Smoak and John Diggle heading to Purgatory (which manifests as Lian Yu) to retrieve Oliver Queen's soul after his untimely death. Lobo's Corrigan interrupts the reunion and, after introducing himself, Constantine remarks, "Not the one I know." When asked on Twitter if this was an intentional reference to the NBC series, Guggenheim replied, "Yes. Exactly."RELATED: Is Arrow's Oliver Queen Transforming Into Another Major DC Hero?

NBC's Constantine ran from 2014 until 2015, lasting just one season. Matt Ryan, who played the series' title hero, appeared on Arrow before joining the Legends of Tomorrow.

"Crisis on Infinite Earths" will return after the winter hiatus. The crossover will conclude on Tuesday, Jan. 14 in Arrow at 8 p.m. ET/PT and in DC's Legends of Tomorrow at 9 p.m. ET/PT. The Supergirl, Batwoman and Flash episodes are now available to stream on The CW.

KEEP READING: Crisis on Infinite Earths' Best Scene Is Now Available to Watch Online