What makes you say that?
mainly because she’s the only combat mage in Equestria.
Though your ages supports my theory that GUIHTD takes place chronologically in Season 1.
Then again, the CMC somehow have no idea how public transportation works, despite having successfully taken the train on their own in “For Whom the Sweetie Belle Tolls” and “The Last Crusade”. Accidentally taking the wrong train would be fairly plausible. Forgetting that they need to make sure they’re taking the train, not so much.
I also remember hearing that the episode was originally written back around season 4 or 5 (when their behavior would have been more plausible), but not greenlit until much later.
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