"Zelkova Strikes Back" is the seventy-second episode of the anime series, Sonic X. It first aired on 12 April 2005 and 18 March 2006 in France and the United States respectively.
- "Gotta Go Fast" - Opening theme (USA and CAN)
- "Sonic X" - Opening theme (AUS, NZ and UK)
- "Gotta Go Fast" (shortened) - Closing theme
The Blue Typhoon arrives at a planet, but Yellow Zelkova attacks the Blue Typhoon and forces it to crash onto the molten surface. Zelkova is equipped with a special energy shield that was built by Dr. Eggman, whom he praises before telling a riddle for Sonic's friends to solve "What is the place we are scared to go at night, but we rest in peace?"
After solving the riddle by answering a cemetery, Zelkova told them that he will take the opportunity to teach Sonic's friends that the molten planet will become their grave by beginning to punch their ship towards the edge of the cliff down into a collecting lake of lava below. Sonic attempts to stop him, but is unable to break through the shield. Picking up where they left off, Zelkova and Knuckles get into a fierce battle, during which Knuckles smashes Zelkova's knee and breaks the spikes on one of his gloves. Using a cable from the Blue Typhoon, Sonic and the others channel lightning to overload Zelkova's shield. Zelkova's mechanical outer body is destroyed, revealing his flesh form beneath. Zelkova attacks, but is knocked into a nearby lava pit by Knuckles.
Pale Bayleaf informs Eggman of Zelkova's demise, mocking the failure of his shield. Shadow and Rouge find a fake Chaos Emerald at the top of the tree, but they hear groaning from its base. They find Leon (from the Resistance in Episode 68) being consumed by the tree, saying that the Metarex betrayed them. He also gives Shadow a memory chip and says it's not too late to destroy the Metarex before succumbing to the effects and dying shortly afterwards.
- The first seventy-five seconds of the episode are cut from the English dub. This cut shows Rouge and Shadow at a bar, the bartender telling them that his place is the last civilized area which has been spared many times, but life is not always pleasant there with the Metarex. The bartender advises them not to continue their mission. Outside the bar, Shadow tells Rouge she does not have to accompany him, to which Rouge says that she brought him here. Shadow says he will find his own transportation if he needs to, and then (at least in the French version) thanks Rouge for helping him.
- In the Japanese version, there is a nine-second scene of Amy talking to Chris, where Chris saying four Metarex ships are right behind them, much to Amy's surprise. That scene was removed from the English dub
- In the Japanese version, there is a ten-second scene of Knuckles in the engine room, activating the Master Emerald. That scene was removed from the English dub
- In the Japanese version, there is a twelve-second scene of Cream talking about how the Metarex could know what they are currently planning, followed by Chris saying they are ready for take-off and Tails giving clearance. That scene was removed from the English dub
- In the Japanese version, there is a twenty-three-second scene of Black Narcissus and Pale Bay Leaf talking about Yellow Zelkova going off on his own without Dark Oak's permission. That scene was removed from the English dub.
- In the English dub, as the Typhoon is spiraling toward the lava planet, Tails says "Pressure's dropping by the second!" That quote was not present in the Japanese version.
- In a scene of the Japanese version, Zelkova asks the crew of the Typhoon a riddle: "What is the place we are scared to go at night but where we rest in peace?" Tails and Amy has trouble solving but which Cream's answers is a graveyard. Zelkova then tries making a grand speech about their doom, but falters and has to be aided by Amy and Tails. Those scenes were absent from the English dub.
- Zelkova's "Super Plasma Shield" used to block Sonic is changed to "Illuma shield" in the English dub.
- In the Japanese version, there is a scene where Zelkova calls Knuckles a hedgehog and Knuckles gets mad, saying he is an echidna. This was absent from the English dub.
- In the Japanese version, Shadow says that the tree-planet they land on is a "dead world/planet" and Rouge gasps. In the English dub, Shadow says that the planet is cold and Rouge "shivers".
- In the English dub, there are six seconds added to the scene were Knuckles is hanging on the rock wall above the lava pit.
- In the Japanese version, there is a scene where Chris is looking forward for one second after Sonic's Spin Attack attracts the lightning bolt. That scene was removed in the English dub
- In the Japanese version, there is a five-second scene of Yellow Zelkova's plant form saying that he will take them all into the afterlife with him. That scene was removed in the English dub.
Title in other languages
|Japanese||メタレックスの正体！？||The True Form of the Metarex!?|
|French||Qui sont les Métarex ?||Who are the Metarex?|
|German||Zelkova schlägt zurück||Zelkova strikes back|
|Italian||Zelknova colpisce ancora||Zelkova strikes again|
|Spanish||¡¿La verdadera identidad de Metarex?!||The true identity of the Metarex|
- There is an extra scene in the Japanese version where Knuckles tries to help Yellow Zelkova from a lava pit, but Yellow Zelkova refuses his mercy and he accepts his death. This could be a homage to how Sonic tried to save Hyper Metal Sonic from a similar scenario in Sonic the Hedgehog: The Movie.
- (Japanese version only) When Sonic and Knuckles are fighting Yellow Zelkova, the Radical Highway theme song from Sonic Adventure 2 called "Vengeance is Mine" plays.
- This episode shows that Sonic is able to move faster than lightning since Sonic can keep himself ahead of the lightning he gathered to attack Yellow Zelkova.
- When the episode first aired in the US, Yellow Zelkova is seen sliding into the lava, but in the second airing he disappears in a gleam of light. Similarly, during the ending when Shadow and Rouge found Leon engulfed in a tree, the camera pans away to see the other members of the resistance sharing the same fate, while the second airing edits out the members to fully grown trees.