Other mistake: The shot before Dredd tells Anderson the terms of the assessment is flipped: you can tell because the judges walking in the corridor have their badges pinned to the right side: with every other judge in every scene of the movie, it's on the left side. (00:10:25)
Other mistake: When Joe shoots the boy at the back of the house, he walks to the front at the same time a woman a few feet away walks toward him with a pram, and there are people in the background. There is no reaction from anyone to the obviously loud gun shot noise - his gun did not have a silencer on it.
Other mistake: When Emma Watson says "get wasted all the time", her British accent is very obvious, especially when she says "all."
Other mistake: In the scene when Lindsey picks up her paycheck, the check is not signed.
Other mistake: When Will is in the club and Lucia's friend is checking his wound she feels around to see if the bullet is still inside his body. She says the bullet is not there so cauterises the wound. Will does not have an exit wound so the bullet must, therefore, still be inside.
Other mistake: In one part of the lifeboat scene, Pi crawls under the tarp to get some supplies, yet he never sees Richard Parker under it.