I am not a fanatic with searching out continuity errors or hanging on to every line hoping it gets answered but one still gets me and I want to know why it was said.
In season 5 when Sun asked Richard if he was there in 1977 and if he knew these people he said yes he knew these people because "he watched them all die".
Now, many people are assuming he is talking about the incident, which would be fine by me. However, if this was the case, when he eventually joined them this season shouldn't he have said something. Or shouldn't Sun have said something along the lines of "you told me you saw them die".
I mean, it's no big deal, but it seemed like a very important line.