Hoo boy, the time travel episode. Those always tend to break the plot. Let's see how much the continuity will be broken here, shall we?
Well, the ninja head to the city of Ouroboros to fight Garmadon, who heads back in time to try and stop the ninja from ever becoming a team, by making it so that the skeletons never capture Nya. Looking to fix the past, the ninja capture Nya and deliver her to the skeletons, but then the present version of Garmadon teams up with his past version to try and kill past!Kai, leading the ninja to steal the Golden Weapons and unite their power to destroy the Mega Weapon, throwing them all back into the present, with the past remaining unchanged.
Various Observations:
-The intro has been updated with adult Lloyd!
-May I just say that it's a spectacularly bad idea to train by fighting with lethal weapons in closed quarters? Who came up with this? Chokun?
-Oh dear, Zane almost killed Nya with his shuriken. At least they both actually react with shock.
-I like the sound effect when the Bounty turns around. It doesn't really make sense, since it doesn't have wheels, but that's the fun part of the gag.
-It looks like the snake vehicles still need maintenance with regular tools, but aren't they alive? I feel like they'd need some special care.
-Hold up, what? Where did Wu come from? He's just suddenly right in front of Garmadon? What did he learn the art of teleportation?
-Why is Nya not in her Samurai X armor? And where's the mech? I feel like both of those would be a significant advantage.
-Good on Lloyd for freezing the Mega Weapon before Garmadon could do something with it. Although I do have to wonder when he learned to use the element of ice.
-Alright, I guess wishing for powers, in this case to power to go back in time, really does work.
-Wait, how did Zane deduce what Garmadon did? The city sinking into the sands does not equal Garmadon having found a way to travel through time.
-And now how did Kai figure out what day they arrived at. Are the writers just telling the ninja what they need to know?
-So Garmadon wants to prevent Kai from becoming a ninja, so that he wouldn't risk the mission to get the third Fangblade, leading to volcano to remain stable, and the ninja to save Lloyd without figuring out that he's the green ninja. Yeah, fair enough, I can see that working.
-Although, if Kai and Nya don't join the team, Cole, Jay and Zane are going to die in that acidic swamp in "Can of Worms", which would in turn jeopardize the mission to save Lloyd ... I think. Maybe Wu and Garmadon can solo the Serpentine, who knows. Still, this plan seems extraordinarily risky.
-Wait, why can we hear the end of Kai and Wu's conversation before Wu even reached Kai? What's going on there?
-At first I was going to comment that Wu is surprisingly quick to believe the ninja when they clame to have time-travelled, but then I remembered that he would know about the Time Twins and Time Blades eventually returning, so maybe he just figured that that was what caused them to go back.
-I love that Jay can just solo the skeletons by now. They weren't that impressive in the pilots, and the ninja are definitely stronger now than they were back then.
-Wow, Zane is surprisingly invested in Jay and Nya's relationship. He treats it being retconned out of existence by time travel with the same gravitas as the world they know never existing.
-Hm, in the altered timeline, Kai wants to stay a blacksmith, but Nya wants to be a ninja. It would be kind of neat if the timeline had split off here, giving us an alternate timeline where Nya's a ninja from the start.
-How do none of the skeletons recognize Gamradon's voice? Then again, Mark Oliver didn't bring his best performance to the pilots, so I guess they would sound different.
-Wait, what's going on here? The wheel just has it's part data printed on. That ... seems like an error that really should have been caught at some point.
-I love Cole saying that Kai would be relieved to hear of his sister's kidnapping, just because it sounds so bad out of context.
-Why didn't we get a mirror match for Cole? Jay and Zane got one, and it'd definitely be better than pilot!Kai's performance after brushing his teeth.
-The echo on pilot!Garmadon's voice makes him sound much better than the actual Garmadon from the pilots.
-"Great Scott"? Did ... Wu make a Back to the Future reference?
-I like that the Sword of Fire and the Mega Weapon are different shades of gold, since the shade was changed between the pilots and the show.
-Wait, what? How can Cole grab onto the Mega Weapon, when that was enough to kill the pirate? Nobody aside from Garmadona and Lloyd can survive the power of Creation!
-Wait, what is Zane saying now? Destroying the Mega Weapon makes it so they never time travelled? Why would that be the case? And why does it work? The Mega Weapon is never destroyed, just shot into space.
-I like that the ninja combine their elemental powers to use Creation. They usually only do this during the Tornado of Creation.
-Wait, why does Llyod act like the Mega Weapon never existed? It has to have existed, else he would still be a kid, Captain Soto and his crew would still be dead, and the Mega Weapon plus the Golden Weapons would not be in space!
-Yeah, the ending of this episode is just completely continuity-wrecking. Just give us an epic battle against Garmadon and the Serpentine at Ouroboros, ending with the Mega Weapon being shot into the space, not this!