Continuity mistake: When Ash takes out his Pokédex to find facts on Quagsire, it and his right hand clip through him. Also, his right sleeve goes from being all white to white and blue and his right jacket strip goes from being present to being absent. (00:02:09)
Continuity mistake: When Ash uses his Pokédex to find facts on Hoothoot, his left index finger is not past the right side of the Pokédex, but in the next shot, it is. (00:03:36)
Continuity mistake: When Ash uses his Pokédex to find facts on Chikorita, his right thumb is not covered and his right pinkie finger is not bent, but in the next shot, his thumb is covered and his pinkie finger is bent. (00:02:54)
Hiwada Town! Yadon's Well!! - S3-E26
Continuity mistake: When Misty says, "I bet it hasn't rained here in months," Brock is holding the map towards the bottom, but in the next shot, he holds it in the middle. (00:07:18)
Hinoarashi! Catch It!! - S3-E25
Continuity mistake: When Misty asks, "Ash?" the combination of the grass and dirt changes. (00:02:26)
Continuity mistake: When Ash is walking to the torchbearer, the people in the background change. (00:03:32)
Continuity mistake: When Ash first uses his Pokédex to learn facts on Snorlax, his right index finger is aligned with another one, but in the next shot, it is not. Also, his right ring finger is not aligned with another one, but in the next shot, it is. (00:07:40)
Hanecco's Jealousy! Battle in Big Prairie!! - S3-E21
Continuity mistake: When Ash says, "There's a couple of Gloom over there!" Pikachu's mouth is open, but in the next shot, it is closed. Also, Misty is not smiling, but in the next shot, she is. (00:01:29)
Big Panic! Kimawari Contest!! - S3-E19
Continuity mistake: When Ash says, "Water!" the puddle near the one under the leaking pipeline is more to the left of it, but in the next shot, it is more to the right of it. (00:01:40)
Continuity mistake: When Ash says, "Misty'll take good care of your Marill, you'll see," Wilhomena is holding her parasol with on hand, but in the next shot, she is holding it with two. (00:09:16)
Kikyo Gym! Sky Battle!! - S3-E15
Continuity mistake: When Pikachu agrees after Ash says, "Someday, I'll go back and see my old friend," his mouth is open, but in the next shot, it is closed. Also, Brock is to the left of Ash, but in the next shot, he is not. (00:06:32)
The Ninja Poke-Showdown - S1-E32
Continuity mistake: When Misty asks, "Brock, what kind of crazy place is this?" her bag is under and next to her, but in the next shot, it's not under her and is 0.33 metres away from her. (00:03:24)
Dai Pinch! Madatsubomi no tô - S3-E14
Continuity mistake: When Zacky is excited to meet Ash, Lizzie's mouth is open, but in the next shot, it is closed. (00:02:50)
Continuity mistake: When Ash and friends turn to look at Growlithe's mansion, Brock's left bag goes from brown to red. (00:02:31)
Continuity mistake: When Arielle lands on the bridge, she is on two planks, but in the next shot, she is on one. (00:03:49)
The Battling Eevee Brothers - S1-E38
Continuity mistake: When Pikachu and Eevee are first talking, the beam closest to the screen is smaller than the others, but in the next shot, it is larger. Also, there is a tree to the left of Pikachu, but in the next shot, there is not. Additionally, Pikachu is next to the plate of food while Eevee is one centimetre away from it, but in the next shot, he is two centimetres away from it while Eevee is three centimetres away. (00:09:48)
Continuity mistake: When Ash brings his first piece of meat into his mouth, another one not being eaten goes from being present to being absent. (00:09:09)
Continuity mistake: When Ash, Misty, and Brock turn to Woodruff after he says for Ash to wait, Ash's right glove goes from covering his thumb to not covering it. (00:02:23)
Continuity mistake: When Officer Jenny is first describing the situation, her strap is not over her right shirt pocket, but in the next scene, it is. (00:05:52)
Continuity mistake: When Ash turns after he wonders how the Heracross will help the Butterfree, the marks on his cheeks go from being present to being absent and then back to present. (00:03:02)
Answer: There are a lot of fan theories around this, but the most comman theme is that Pikachu had another trainer before Prof. Oak, who gave him to Ash. Pikachu didn't appreciate being handed over.
Ssiscool