Other mistake: When the Doctor tells the Atraxi "Oh, you're not the first lot to have come here, there have been so many," one of the monsters shown from their scan of Earth is a group of Ood. Even if in one of their uprisings they attacked the Earth, it would have been in the far future. The Doctor has had no encounters with them on Earth, and he knows them to be peaceful, so why would they be amongst the aliens who have threatened the planet? The only Ood who has been to Earth at this point is Ood Sigma, and he didn't come to attack. In addition, a group of Hath is also shown. These aliens have never been seen on Earth at all. (00:53:30)
Revealing mistake: When the Doctor travels back in time after being shot by the stone Dalek, falls down the stairs and tells himself that he has 12 minutes to live we never see either of the 2 Doctors' faces onscreen at the same time, and if you look at the hair on the Doctor that's dying it is completely different to Matt Smith's. That's because it is Gordon Seed, Matt Smith's stunt double.
Factual error: When the Doctor spots Rory taking a photo of Prisoner Zero, we're shown a brief close-up of Rory's hospital identity badge. The date of issue is given as "30/11/1990". The main body of the episode is set in 2008, two years before Rory and Amy's wedding in 2010. It's further established in the episode that Rory and Amy played together as children after her first meeting with the Doctor in 1996, with Rory observing that Amy made him dress up as the Raggedy Doctor. Rory could not possibly have worked for the hospital for eighteen years at the time of the episode. (00:33:10)
Continuity mistake: After the Doctor steps through the hologram of his past selves and introduces himself to the Atraxi, in a wide shot, there's a red jacket lying on the ground to the left of Rory. In a close-up of Amy and Rory immediately following, the jacket has suddenly leaped into Rory's arms, to join the other clothes he's holding. When the Atraxi flies away, the red jacket is back on the ground again. (00:53:55)
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. (00:04:54)