So, Sora and Riku go through memories of worlds they have previously visited in Castle Oblivion, but when did Riku ever visit Atlantica, Wonderland, Olympus Coliseum, and Halloween Town? 

 

Asking this out of boredom and curiosity. 

He may have visited them  but just not shown it in kh1. 

Magic~

I wish they showed Riku in Atlantica.

Dem abs.....

I think he either had visited them during Kingdom Hearts 1, or maybe when he was working with DiZ...

 

That, or he never went to them at all, which is possible.  Really, there's no good explanation for why he visits those worlds in Re:COM and no where else.

Well it's fairly likely he went to Wonderland in KHI, as he is probably the one who kidnapped Alice. As for Atlantica and Halloween Town and such, who knows, could have visited them at some point.

I want to say it was because Sora visited them before and he was just redoing Sora's journey, but then I realized that idea wasn't made until KH3D. So who knows.

It could go either way.  If it was important to show he did, they probably would have.

I'm guessing he visited the worlds when Sora did but not in the same order. Why he went to the other worlds was because he was working for Maleficent and capturing the princesses. 

He probably visited them in KH1 with Maleficent since she was the one who kinda showed him how to use darkness and travel with those dark corridors. He had to collect the princesses as well, so he most likely went in a different order than Sora a few times. I dunno....I say he basically went with Maleficent

Riku Might visit Atlantica, Agrabah, Wonderland, Olympus Coliseum, Pride Lands, and Other Worlds in KH3 but on the Good Side he might make New Friends their Such As Simba, Ariel, Hercules, Mulan and others.

He didn't.......but in COM, Nomura forced him to go.

I think he went through Sora's memories that is why he visited the same worlds as Sora did although he never visited any.

Nomura logic /shot

 

Riku might have visited them during KH1, they just didn't show it.