Factual error: In the episode, the Titanic is shown to have sunk the same day it left England. The actual Titanic left England on April 10 and didn't sink until the night of April 14, almost 4 days later. Plus they show it leaving from London, not Southampton as it did. (00:11:40 - 00:15:30)Casual Person
Plot hole: When it is revealed that Chris's teacher was never born, Teacher Doug introduces himself, despite the fact that if Chris's teacher was never born, Doug would already have been teacher for the entire year, and therefore all of the students should know him and he would not have to introduce himself.