Board Thread:Ninjago Wiki News/@comment-35245651-20180704072956/@comment-26537965-20180831201628

Warptoad wrote: Ninja72 wrote: Warptoad wrote: That's not a continuity error, it's just a picture. It's weird that it's from the intro, but it's not like we can't assume that they just happened to take a group picture that looks like that. I think he meant that since their new designs are because of time travel, there should not be a picture with their old designs. That was just a fourth wall joke.

https://twitter.com/TommyAndreasen/status/1017109278128328705

They look different for the same reason Garmadon looks different in Season 3 than the end of Season 2. He just does, don't worry about it

You can make up a reason yourself. The Hagemans said this is the canon explanation though, so there is contradicting information on this, just like on whether or not Ninjago is one of the Sixteen Realms.