Trixie had a great sense of direction. So clearly, if she'd ended up facing a wall, it was the street that had been wrongly built. Those crystal ponies, who couldn't even build a road right. But it wasn't a problem, if the Empire's misguided decisions in building their cities rendered her superior sense of orientation useless then she'd just have to ask for directions.
She just had to find someone in the cold, empty, dusty back alley devoid of any other pony. The disembodied horn on the ground would have to do.