Now that the four-way crossover between Supergirl, Flash, Arrow and Legends of Tomorrow has come to an invasive close, the hunt begins for DC references and easter eggs! One moment in particular saw Brandon Routh referencing his own Superman Returns past, but don’t expect Supergirl to be let in on the joke just yet.

You’re warned of full spoilers through tonight’s “Invasion!” crossover close, but the presence of another Super-star in Melissa Benoist’s Kara Zor-El naturally warranted a nod or two toward Brandon Routh’s own starring role in Superman Returns in 2006. As such, a quick wink in the final scenes saw Ray Palmer noticing that a dressed-down Kara Danvers “really kind of looks like my cousin,” clearly alluding to Superman and Supergirl’s familial tie.

Don’t read too far into the idea of Ray’s cousin cropping up in the Arrow-verse (and looking suspiciously like Melissa Benoist), however, as execturive produrcer Marc Guggenheim told reporters (h/t IGN):

With respect to the cousin line, it’s sort of like last year on Legends we did the prison break, it was like, I said to the writers, ‘If we don’t make a Prison Break joke here with Wentworth, we’re not doing our jobs.’ I was like, “If we have Brandon and Melissa share the screen and we don’t make some sort of joke like that, we’re not doing our job.’ The truth is, that joke existed on Arrow originally and then a certain scene got cut so then I moved it over to Legends; I just kept moving it back and forth. I’m like, ‘I’m getting it in one of these episodes.’

Prior to Supergirl making the leap to The CW (but after announcement of the Flash crossover) fans wondered if The CW might return the favor with an Arrow-verse iteration of Kara, perhaps even in an alternate comic identity like Power Girl. Executive producer Andrew Kreisberg even answered the question again in light of this week’s crossover, saying:

We hadn’t discussed it formally, but I think that certainly after these three episodes, there’s literally no limit to the things that we could do. There’s still an endless treasure trove of DC Comics characters, and stories, and titles that we haven’t even come close to touching yet. We’re certainly not wanting for ideas for the future. We know that they’re out there for us.

Granted, the crossover’s closing minutes made a point of enabling easier access for Kara to travel back and forth between universes, negating the need for another iteration of the character, but might Routh’s reference pay off again? Will Tyler Hoechlin’s Superman join in on the fun, next crossover?