Plot hole: Tru and Lindsay are making all their plans for the reunion on the day of the event, including whether or not they will attend and whether or not they will bring dates. But a high school reunion requires an RSVP in advance, just like a wedding or bar mitzvah. So they should have had to figure out their plans weeks earlier.
Plot hole: Why did Tru have the reunion invitation on her desk the morning of the event? It seems as if she had received it that day, since Davis asks if she's going and she says no and throws it away. That's something you'd do with the invitation upon receiving it and deciding not to go. But it doesn't make sense for the invitation to have gone out the day of the party.
Continuity mistake: The first time Tru goes to the reunion, she wears a colorfully decorated beige blouse with a knee-length black skirt. But when she jumps into the pool upon seeing Candace's body in it, she's suddenly wearing a white top and full-length pants, which happens to be the outfit she wears the second time she goes to the reunion.
Plot hole: At the end of the episode, Lindsay says that her note made one man a liar and another man gay. But how does she know that Craig lied? The first time, Craig said that he didn't get the note, and also demonstrated that he had no idea who Lindsay even was. The second time, Tru intercepted Craig and asked him to be nice to Lindsay. So he again told her that he didn't get the note, but also said that it's a shame he didn't get it, because she's really amazing, but it's too bad because now he's married. So he barely lied to Lindsay, and she would have no way to know about it. Tru didn't hear what Craig said, so she wouldn't know if he lied, either, and even if she did she wouldn't tell Lindsay, because the whole point was to make her feel better about the situation.
Plot hole: How did Candace get voted Reunion Queen the first time around? She acts like a total bitch to everybody we see her in scenes with, all we ever hear about is how many people hate her and probably wouldn't mind seeing her dead, and her comments when she accepts the award ("I can sort of remember some of you.") make it clear that she hasn't kept up with anyone.
Plot hole: In the episode "Closure," Harrison told Tru that he had lost interest in Lindsay, and was going to break things off with her. In this episode, they're still all coupley. Moreso, in fact, than earlier. We were never shown any developments in Harrison and Lindsay's relationship between the two episodes.
Chosen answer: The next episode shows that Tru didn't meet Luc after all, even though she should have been in work by the time he showed up. I think the answer is that the writers don't actually know.
DavidK93