The three pirates Guybrush meets at the crossroads (the treasure hunter, the sword master and the thief) are all encountered earlier in the game, during the second chapter, Siege of Spinner Cay. They are the pirates assaulting LeChuck, thinking he has one of the golden artifacts. Apparently, the treasure hunter later died of a shot by a cannon, the sword master got decapitated and skewered by a sword, and the thief's hands were cut off.
The three areas in the Crossroads (Swordfight, Treasure Hunt and Thieves' Den) are references to the Three Trials that Guybrush had to complete in The Secret of Monkey Island (1990) to become a pirate (swordplay, treasure hunting and thievery).