Factual error: When Eisenheim is at the Vienna rail station, catching his train after the Crown Prince has died, the overhead electric cables of the modern railway are visible in several shots.
Factual error: When the narrator says Eiseinheim bought a theater, watch the houses on the background, on the right side of the screen. One of them has a visible modern antenna on its roof.
Answer: You never see the sword closely enough to notice if Eisenheim took them during the performance. It is likely that he did not since this was a bit early in his planning (if he had started at all) and the Crown Prince could easily have noticed and replaced them or investigated that they were stolen. It is more likely than Sophie took them after the Crown Prince was passed out and then planted the green one in the stable and the red one in the folds of her dress.
Zwn Annwn