Mystery at the Lighthouse - S1-E13
Other mistake: When Ash and friends are first seen walking on a path, Pikachu's cheek pouches are missing. (00:01:14)
Mystery at the Lighthouse - S1-E13
Other mistake: When Professor Oak goes to rotate his monitor, his right index finger is intermittently not coloured in. (00:09:15)
Mystery at the Lighthouse - S1-E13
Other mistake: When the front of the Kabuto costume falls off, the part of Bill's body above his arms is missing. (00:12:34)
Mystery at the Lighthouse - S1-E13
Other mistake: When Brock turns his head to the costume, his nose is missing. (00:12:47)
Suggested correction: Agree with the other correction. Dropping details, such as facial features like a nose or mouth, and simplifying character designs is a very common and encouraged drawing/animation technique to imply distance. This isn't something the animators would just overlook. It was a deliberate decision. Ash and Misty similarly look somewhat less detailed than they do in closer shots. At best, this would be a deliberate mistake, but I personally think it falls under the umbrella of "suspension of disbelief" and shouldn't be considered a mistake given it's a stylistic choice to imply distance.
Suggested correction: His nose isn't seen because he is far away from the camera.
Mystery at the Lighthouse - S1-E13
Other mistake: When Bill says, "A meaning for all Pokémon, and a meaning all of us humans too," a Sandslash on a screen has an entirely yellow head and has black pupils with white sclerae. Sandslash actually have the lower part of their head coloured cream and have their white pupils with black sclerae. (00:14:01)