Revealing mistake: In 'The Pandorica Opens', in the scenes where the Cyberman arm is shooting at the Doctor and Amy, just after the Doctor jumps out to draw its fire, Amy leans on the Pandorica and you can see it bend in, revealing that it's made out of plastic or something.
Continuity mistake: At the beginning, when the Doctor takes Amy to planet One, he holds out his hand for Amy to take hold of when they're about to leave the TARDIS. When you see her from the back, Amy lifts her hand wearing her red fingerless gloves. But when it switches shot and faces Amy from the front, she takes the Doctor's hand wearing no gloves. When she steps out of the TARDIS, her gloves are on again.