The Mystery Menace (Japanese: ちかどうのかいぶつ!?Phantom of the Sewers!?) is the 102nd episode of the Pokémon anime. It was first broadcast in Japan on June 24, 1999 and in the United States on May 6, 2000.
Spoiler warning: this article may contain major plot or ending details.
Template:Incomplete synopsisAsh and the group have finally made their way to the city of Trovitopolis, which should lead them right to Trovita Island and the next Orange League gym! Everything seems normal until the earth cracks right beneath their feet and they find themselves in the sewer underground, and not alone. There seems to be some sort of a “monster” living there which turns out to be a giantBulbasaur the town's mayor once abandoned there. Will Ash, Misty and Tracey be able to find it, before it finds them?...
Major events
Ash temporarily adds Muk to his team. It is implied that he returns it to Professor Oak at the end, but it isn't shown.
Professor Oak's lecture: Pikachu's Rescue Adventure. Oak talks about the second Pikachu short which was upcoming when this episode was first shown (released July 17, 1999 with the second movie). He says that new Pokémon will be seen, specifically Elekid and Bellossom, as well as "others."
Similar to Bulbasaur's Mysterious Garden, this episode features a Bulbasaur and has the word "Mystery" or "Mysterious" in the title, alluding to its Japanese name.
Pikachu can be seen riding it's infamous pink surfboard in one of the scenes.
Errors
After Ash, Misty, and Pikachu pull Tracey out of the rock, he thanks them and realizes that he's sitting on top of Ash. But when Tracey was freed from the rock, it shows Ash falling away from Tracey and he falls on to the ground rather than Ash.
When Tracey presents the "monster" to Ash and Misty, a back shot of the Bulbasaur shows it without its blue collar. Seconds later, it's seen wearing it in a full shot.
The straps on Tracey's backpack are painted orange instead of black when the monster first attacks.
When Misty finds Togepi, the blue triangle symbol on Togepi's body disappears.