Goofs

When Minion confronts Megamind about dating Roxanne Ritchie, Megamind disables Minion's arm. When Megamind says maybe he doesn't want to be the bad guy anymore, Minion recoils with a gasp and lifts both arms in surprise which he shouldn't have been able to do with a disabled arm. Minion is then shown driving away on his Segway, and his arm is once again disabled.

Early in the movie, when Roxanne is asking Megamind where he gets the equipment for his super villain lair, Minion's hand is sometimes on the back of her chair, and sometimes missing, between shots.

Megamind sabotages the Metroman museum with a huge pile of explosives at the statue's right foot, some of which are visible on top of the foot. When he takes the elevator down with Roxanne, the foot is visible and no explosives are present at all.

When Megamind transforms into different forms, his voice changes to match the character. However, when Megamind transforms into Bernard, his voice remains that of Megamind's. This is explained through the watch recording the warden's voice during Megamind's escape from prison. He didn't get the chance to record Bernard's voice in the rush to replace him in the museum and had to use his own voice.

When someone disguises as another through the watch, the person is physically similar to the impersonated one, with exception of the eyes. This is seen when Megamind impersonates as the Warden, Metro Man and Bernard. But at the end, when Minion impersonates Megamind, his eyes are green, when they should remain brown, as Minion's are.

Minion isn't actually a person, so the transformation works differently on him.

When Megamind dehydrates Bernard and then assumes Bernard's likeness as his disguise, he scoops up Bernard's eyeglasses and cellphone from the sky-walk. In the credits extra scene, when Bernard pops up out of the washing machine after being re-hydrated, his glasses are askew on his face.

When Megamind, disguised as Bernard, is in the library with Roxanne, the book he reads before the next scene is titled 'Megamind Unmasked'. The back of the book is actually a summary of a different book, 'The Happiest Me I Can Be' which is a book not seen until later into the movie.

After Tighten rips the door off the invisible car, Megamind pushes the lock down. He's holding onto the door with one hand and the defuser gun with the other, leaving no hands free to do this.

He obviously let go of one or the other. Perhaps he held the gun between his knees.

During Megamind's third fight with Tighten, there is an advertisement on one building that parodies Barack Obama's "Yes We Can" campaign poster, with an illustration of Megamind shedding a single tear and the words "No You Can't" below. However, when Roxanne is confronted by Tighten at the fountain, the poster is gone.

It's unknown if Metro Man told the people of Metro City that he was still alive.

For some reason, Roxanne didn't recognize Megamind's voice when he was disguised as Bernard.