100,000 BC - S1-E1
Character mistake: When Ian is trying to escape from the TARDIS in episode 1, he says, "He closed the door from over there, I saw him." It was in fact Susan who closed the door.
Character mistake: Dr. Kagan, who's a scientist and should definitely know better, points to Earth's solar system on the chart and calls it "our galaxy." This is roughly the equivalent of mistaking a dot this size [.] for the entirety of North America. (00:23:30)
Character mistake: THE MEXICO ADVENTURE (part 76): Sean Donnelly confronts Peter in a threat, forcing him to call Felicia collect - in the U.S. - insisting she fly down immediately. Sean then hands Peter a piece of paper with a phone number on it, and Peter calls the operator. The number Peter gives the operator is the same number Felicia has called her grandmother collect with - in Texas - several times - not Frisco's apt. in New York, where Felicia is staying.