Trivia: When Megamind as Bernard is in the library with Roxanne, the book he is reading ("Megamind Unmasked") has a description on the back of a self-help book entitled "The Happiest Me I Can Be". This is the same book that Metroman read (shown later in flashback) that caused him to decide to cease to be a hero. (00:43:30 - 01:08:30)
Trivia: During Megamind and Metroman's final battle in the beginning of the film, just after Megamind yells at Minion to fire the death ray, Metroman can be seen (from the crowd's point of view on the giant monitors) to fade out slightly from the observatory and fade in just behind Megamind's right shoulder. This corresponds to, and foreshadows, Metroman's flashback shown later. (00:17:50)
Trivia: Amongst Megamind's loot in the office is the Ark of the Covenant from "Raiders of the Lost Ark" as well as several Oscar awards.
Trivia: Director Tom McGrath plays the voice of the foster father of Metroman and one of the prison guards.
Answer: The characters are only 'disposed of' so that they won't be able to reveal Megamind's deception. Remember, the warden wasn't killed and neither was Megamind when the warden was transformed into him. It is not necessary for the device to function that the individual being copied be eliminated.
Phixius ★