Character mistake: In the first scene inside the Prometheus, after she comes out of deep sleep, Vickers asks David for a robe, and asks "how long?" meaning how long have they been asleep. David, a robot, answers "2 years, 4 months, 18 days, 36 hours, 15 minutes." The actual statement from this highly precise robot character would have been "2 years, 4 months, 19 days, 12 hours, 15 minutes."
Character mistake: When John meets his clone in the rundown house he lives in, the clone has a British accent and tells him his story. John has an American accent. When the real John tells him "I'm not like you, I had a wife, a family, a daughter" he mistakenly uses a British accent.
Character mistake: When Michael goes to the antique shop, the sign out front is spelled wrong; it reads "anitques."