Beauty and the Beast!? Dirteng and Joi-san - S6-E37
Continuity mistake: When Nurse Joy walks to the window at the beginning of the episode, her chair is positioned on the second row of tiles from the window while her desk is positioned on that and the first row of tiles from there, but when Ash and friends watch the footage of the shot, Nurse Joy's chair is positioned on the third row of tiles from the window while her desk is positioned on the second and fourth rows of tiles from there. Also, the way Nurse Joy braces when the wind blows changes. (00:04:54)
Answer: There are a lot of fan theories around this, but the most common theme is that Pikachu had another trainer before Prof. Oak, who gave him to Ash. Pikachu didn't appreciate being handed over.
Ssiscool ★