When I first heard Lars speak I was a little disappointed that they had so obviously used the same voice actor who does Fry (Billy West) but didn't think anything else of it and totally missed
most of the other clues about Lars' true identity. (I caught his "what?" when the Professor mentioned that time-duplicates were always doomed during the wedding but still didn't twig to its significance.
) So I was completely (and pleasantly) surprised by the reveal at the end.
I'm not sure if there's a word for it but I find myself really enjoying those out-of-left-field sudden happy resolution to a seemingly hopeless situation
-type endings (e.g. the 'closet' in the apartment episode from the first season) when I suspect they actually should annoy me. I'm obviously just a big softy.