Supergirl's Melissa Benoist paid a visit to the set of Riverdale and was snapped hanging out at Pop's diner with Betty and Veronica. Neither of these shows will be back on the air until October, but filming is well underway for the majority of The CW's comic book adaptations already. Supergirl, the other Arrowverse shows and Riverdale are all filmed in Vancouver - making Arrowverse crossover episodes a lot easier, and allowing for this kind of fun set visit between series.

It would also theoretically make it possible for The CW to combine Riverdale with their larger comic book universe - although Archie and the gang aren't part of the DC universe when it comes to comics. However, Riverdale showrunner Roberto Aguirre-Sacasa has previously said that he would love to see a crossover with the Arrowverse at some point (at WonderCon earlier this year) and he further teased just that, by way of a photo showing Benoist hanging out with the Riverdale cast.

Related: Riverdale Season 2 Preview & Poster

The photo was posted to Aguirre-Sacasa's Twitter, showing Benoist, Lili Reinhart, and (we assume) Camila Mendes, all in costume and sitting at a table at Pop's Chock'Lit Shoppe. The shot is taken through one of the cameras on-set, and is captioned "Look who dropped in to #Riverdale for a visit! Worlds colliding!! Can a crossover be far behind??".

The tweet, especially following Sacasa's comments at WonderCon, has sparked speculation that Supergirl could appear on Riverdale in the upcoming second season. However, it's difficult to imagine quite how these two worlds would combine organically. Riverdale may be a comic book adaptation, but it doesn't include any superheroes - though, dream sequences, alternate realities, and the multiverse do mean that anything is possible across The CW's most popular shows.

Despite the speculation about a SuperDale episode (as the potential crossover has been dubbed by fans), it's unlikely that this tweet is actually evidence that such a crossover is on the way. Not only are both shows filmed in Vancouver, but Benoist and Reinhart are friends, meaning that this is likely nothing more than a friendly visit between sound stages during a quiet moment of production. If this is the case, Sacasa's caption can be taken as more of a lighthearted joke than a serious hint at a future crossover.

Still, there's no doubting the power of fans on the internet - and given that the creator has previously said that he would love to do a SuperDale episode, he may also be hoping that the fan response to this image could be enough to encourage producer Greg Berlanti to seriously consider a real crossover episode. It's likely that the fandom will be divided on this one - but if nothing else, it's a fun photo that captures how close The CW family can be.

NEXT: Arrowverse 2017 Crossover Premiere Date & Details

Supergirl season 3 premieres Monday, October 9 at 8pm on The CW. Riverdale season 2 premieres two days later on Wednesday, October 11.

Source: Roberto Aguirre-Sacasa