I know everybody is busy talking about the character design, but let's analyze the background real quick. >Flag of Celestia's cutie mark behind the bed
Something tells me this meant as a replacement for the actual flag of Equestria from the show. Interestingly, the color of the room itself is a similar cyan to the classic flag. >Rainbow dash cutie mark poster
Looks like a wonderbolt picture next to it as well. Maybe Rainbow Dash is lead flyer by now? >dreamcatcher hanging on the wall
Either something related to Luna's dreamwalking abilities, or it's a diversity thing and this is some kind of American Indian pony. The progressive showrunners hate the idea that ponies are white people, so expect them to ignore other creatures like buffalo and zebras and just make pony characters that are obviously "ethnic". >Mane 6 dolls on the shelf
Not much more needs to be said on this one, it's just obvious audience pandering. Nobody in the show ever gave a single shit about the bearers of the Elements of Harmony, why would a character have dolls of only these specific ponies now? Also, the Twilight Sparkle doll is the same height as the others... unicorn Twilight? Or maybe it's supposed to be starlight. If it's unicorn Twilight then that makes absolutely zero sense, nobody in-universe should remember or care about her pre-ascended form. >Twilight, Fluttershy, and Rainbow Dash cutie mark buttons on her saddlebag strap>Twilight cutie mark design on her saddlebag
Yeah, this pony is some kind of in-universe massive Mane 6 fangirl. She has dolls, posters, buttons, saddlebags all covered in their iconography.
This also means that this movie is definitely, absolutely, for certain set in G4 Equestria as we know it, with Celestia, the mane 6, and probably the Wonderbolts too. Hard to guess if this is set during the bulk of the show or after Twilight becomes head honcho, but my guess is the latter.>piano sitting on the ground in front of her bed
Incidental background object, or maybe this character is musically-inclined? Impossible to guess at this point. >blank flank
Since we know for sure that this is G4 Equestria, it's notable that this pony is a blank flank. They're probably "high school" age, AKA a teenager or older kid.
One final thing to note, there's something taking up the left portion of the frame which the character is looking at. My guess is it's a mirror, and the character is currently posing in front of it admiring her saddlebag. First day of school type thing, or something like that.