Pokémon "The Legend of Dratini" (non-existent unaired English dub of anime episode; 1997)
"The Legend of Dratini" was a controversial episode of the Pokémon anime that aired in Japan in 1997, but was never broadcast outside of Asia. The episode was banned by the American dub company 4Kids following a controversial scene, which included Ash being held at gunpoint. This, unsurprisingly, did not get past the 4Kids censors, and thus did not air. As all countries outside of Asia air dubs based on the English version, it was never shown outside of Asia.
4Kids used footage of this episode in the Pokérap which means that they likely got the episode from Japan at some point. 
The episode being dubbed in English was later confirmed to be false by Eric Stuart, voice actor of Brock and James in the Pokémon anime. The Broadcast Standards and Practices division of the television network disapproved of the episode - thus, it was never dubbed and remained unaired.
- The Pokérap itself. Retrieved 21 Jan '18
- Facebook video of Eric Stuart at Anime Midwest '15, disproving the existence of the dub. Retrieved 28 Aug '18