The Topic Train is a cybernetic mass transit service that runs on Choco Express railroad lines, which lie adjacent to the mystical Threads of Conversation. It stops at Route 50 Grand Central Station, which is located just south of the Chat Tower. The Topic Train is best known for its frequent derailings in the Chat Tower, particularly if the chat lobby is packed with newbies or spammers. Chat-roleplayers such as MV, Zoker, FishPaste, Sasori, and occasionally hijack the Topic Train with their roleplay-battles, generally causing other members to flee the wrecked train and the lobby. At other times, more longstanding members will hijack or derail the Topic Train. The most common cause of a Topic Train derailment, however, is a chat flood, as trains do not function very well in water.
In the Route 50 Saga, the Topic Train is the standard means of transportation between websites. It also has a station in Derpderp Forest, not unlike the Phantom Train's station in Phantom Forest in FFVI.