The most recent episode of The Flash showed Barry Allen (Grant Gustin) acclimating to life behind the bars of Iron Heights, but while the episode set up a new normal for the hero and those he is closest to, it also revitalized some of this season's key mysteries.
While most fans of The CW series were excited by the reappearance of the mystery waitress who chatted Barry up at his (failed) church wedding during the Supergirl portion of "Crisis on Earth-X", there just might have been another clue dropped in the episode, this one about Barry's time in the Speed Force. Some fans on Reddit noticed that, when he was keeping track of his days in prison, Barry didn't use a forward slash mark to create "five" with his hash marks. While most just saw this as another borderline-weird trait of Barry's, it actually could be a subtle hint tying back to the mysterious symbols Barry was seen scrawling on any flat surface during the season premiere -- and the symbols the Mystery Girl was writing in her journal this week.
We've previously speculated that Barry was not simply trapped in the Speed Force, but was actually sent into the future, especially considering the ties that the classic comic book story arc "The Trial of the Flash" has to the future. In that speculation, we also considered that the symbols Barry was writing everywhere could be a form of Interlac, a language referred to as "the intergalactic universal language of the 30th century" in comics. Supergirl fans have seen Interlac symbols as graffiti on the alien bar that the characters hang out in, but they've also seen what appears to be Interlac on Mon-El's Legion of Super-Heroes ship.
While the symbols Barry is seen writing aren't an exact match for Interlac as seen in the comics, much of what he's writing is strongly similar. Barry's symbols could very well have the differences due largely in part to handwriting. Even with the English language, no two people write letters exactly the same, a point that The Flash subtly drives home with Barry's lack of forward slash for his hash marks. Additionally, we also see the Mystery Girl journaling in the same symbols. This gives a little more credence to the idea that not only is she from the future -- and potentially Dawn Allen or Jenni Ognats -- but that handwriting changes the look of Interlac. While the Mystery Girl's notations are immediately identifiable as the same symbols Barry was writing, they also look subtly different.
If the mystery symbols do turn out to be Interlac, it will be interesting to have seen how handwriting and personal quirks change the appearance of the language. That really would leave us only with one question: is this house really bitchin'?
The Flash airs Tuesdays at 8/7c on The CW.