SPOILER ALERT for anyone who has not yet watched Megamind.  In which case, it’s been ten years.  You should probably watch it.

Although actor Will Ferrell’s mispronunciation of Metro City began as a bit of a joke-- a French designer on the team had pronounced it "Metrahcity,” and Ferrell loved it-- director Tom McGrath told him to run with the idea.  In a 2010 interview with the Wall Street Journal, McGrath explained that Ferrell was inspired by the concept. 

“This guy [Megamind] wasn't really formally educated and would mispronounce words,” McGrath said. “Will took that kind of handle and ran with it.”

The fandom has taken that idea further by developing a pseudo-canon fan theory that Megamind learned a large number of words by reading.  After all, although he’s shown in a cell with other inmates when he’s an infant, by the time he is old enough for grade school-- presumably six years old or so-- we see that he’s locked in a cell alone.  By the time he is an adult, of course, he’s being kept in a sort of mental-ward-esque solitary confinement cell.  Given that his tenure at school was very short and that hardly anyone except Minion willing interacts with the blue alien throughout much of the film, we can assume that Megamind has had very little in the way of formal education and socialization.   Hence why he might have to learn at least some of the English language from books without ever hearing the words pronounced aloud.

Plus, you know, it gives us the concept of Megamind being a book lover, which I really, really need to be a thing now. 

Next Page Please by elixirXsczjX13 on DeviantArt

Another theory that offers a supplemental reason for Megamind’s occasional odd pronunciations, in addition to his upbringing, is the simple fact that he is a different species of person.  You see, along with choosing to have Megamind mispronounce certain words, Will Ferrell also used his full (and extremely impressive) vocal range to voice the character.  Megamind’s tone is usually a tenor, but sometimes rises nearly to an alto or swoops down into reverberating depths.  This combined with his odd pronunciations has lead many fans to conjecture that maybe Megamind’s vocal cords, larynx, and even mouth may differ from that of a human, therefore providing a wider range of vocal tones but also making certain human sounds difficult to emulate.  That would explain why he manages to pronounce “school” correctly while picnicking with Roxanne in the park; it isn’t that he doesn’t know how “school” is supposed to be pronounced, it’s simply that he has to put conscious effort into doing it.

Ok, today I accidentally said this “I have many drugs”

But I ment to say “I have many grudges”