Kaito also seems to find out that Shuichi/Subaru is wearing a voice changer.
I have also been thinking about that! Why did Aoyama let Kid find out about this? What is the point in him meeting Okiya/Akai. Especially after what happened with Sera. Is he going to meet Haneda Shukichi next?
What really shocked me was finding out Akai and Kid's father have the same voice actor in the anime! I went back nd checked and it has always been this actor for Toichi. I am getting a bit suspicious that there may be some connection to the Kuroba's and Akai's family. Just like it has been confirmed there is a connection between Shinichi and Kaito. (Aoyama confirm this 2 times of the first time he suggested he might not be able to go into it the second time he didn't add that so I'm hoping he's decided to write it in somewhere)
Or maybe Hakuba's family since both their mothers are British. Could be interesting but I don't think this is the case though.
Something else to think about is he disguised himself as Shiho and listened to her voice. He is probably going to notice her features and voice are the same next time he sees her. That is if he didn't already notice from the beginning.
Really for someone who is not supposed to get involved with the main plot he's getting awfully close to it. I guess that could also be why he is the red herring of the series (Kid's Screenname during the magic lovers case)