Crisis On Infinite Earths: 36 Easter Eggs, Cameos And References You Probably Missed
12. Lucifer
Another neat little nod to one of DC's non-Arrowverse shows, the devil himself showed up as Tom Ellis' Lucifer Morningstar made an ever so brief appearance to assist John Constantine with planning a trip to Purgatory.
It was a cameo that came as a pleasant surprise - and the banter between the pair was totally in-line with both of their characters - and it also confirmed that Lucifer inhabits Earth-666. Of course he does.