Jay Wolpert came up with the idea, not present in the novel, that Mondego and Dantes started out as best friends. His logic was that it would work better as a 'buddy' film that turned sinister. Wolpert believed that when a friendship soured, the hate generated was both more terrible and more believable.
The Count of Monte Cristo was one of Mark Twain's favorite books. When Twain toured Europe in 1867, he made a special stop to see the prison, Chateau D'if. The Adventures of Huckleberry Finn contains a humorous spoof of Monte Cristo.
The scene where Morrell goes to Villefort for Emdond's release has a tragic twist in the book. Edmond is accused of being a Bonapartist, and Morrell is himself a Bonapart supporter. The plea is made during the Hundred Days when Napoleon had returned to power. Thus, with Villefort's encouragement, Morrell is convinced that the best way to secure his release under Napoleon's regime is to claim in a letter that all the charges against Edmond were true, thus making him a loyal servant of the Emperor. Villefort; being a stout Royalist, and far from convinced that Napoleon's return would be permanent; never delivers the letter to Napoleon, instead simply adding them to Edmond's case file, thus essentially proving the state's case against him when King Louis XVIII is restored to power.
The trivia items below may give away important plot points.
The scene involving Villefort trying to kill himself and Monte Cristo asking him: "Did you think I'd make it that easy for you?" was shot in two versions. Director Kevin Reynolds thought the other version, where the gun was actually loaded, worked better and put it into the original cut. However, some test audiences, without the knowledge of the existing footage, indicated it would be better if the gun was not loaded, so the scene in the final cut was inserted.
During one of the fencing scenes between Jim Caviezel and Guy Pearce, a move was performed incorrectly and Pearce was actually stabbed through the skin on his side. They took him to a hospital, and after he was patched up, he was bragging about the wound proudly, while Caviezel apologized profusely the whole time.
In the book Fernand is publicly humiliated by the exposure of his old crimes and he commits suicide. Villefort is driven insane and Dantes leaves him that way. Danglars loses his wealth, his wife, and his daughter thanks to Dantes.