If everyone from nearby carriages doesn't know Kaito is deathly afraid of fish, they were probably deaf during the salmon for food phase (Heiji rigged one to drop on him) or new.

Also Kaito is routinely found clinging to walls or the ceiling by his fingernails, apparently out of sheer boredom, and if asked will inform people that the floor is lava and he trying to get from one end of the train to the other.

If he's not there, he's in the game car, half upside down, doing improbable shuffles with cards, or cheating at games with Conan and Heiji