Continuity mistake: Jessie seems completely surprised when she's told that Voltorb can explode, but in The Ninja-Pokemon Showdown (Season 1, Episode 32), not only did she and the others find out what Voltorb are, they were all affected by the explosions as well.
Continuity mistake: When Dr. Proctor says that he has been unable to refuse requests from young girls, the yellow clips on Misty's suspenders turn red like the suspenders. (00:03:22)
Continuity mistake: When Ash, Brock, and Misty rush to find a Pokémon Center for Pikachu because he has fainted, they leave their backpacks behind. When they arrive at the hospital, they suddenly have their backpacks with them. (00:02:26)
Continuity mistake: When Ash realises that something happened with Pikachu, his bag is below the second-highest plank on the bench, but in the next shot, it is aligned with it. (00:01:27)