Of all the great guest stars during Season 2, Tim Conway ended up winning the award for his role here as Bucky Bright. Conway, the former McHale's Navy star, was funny in the role, but I would hardly call his delusional performance as memorable and award-worthy.
Michael Sheen has been mostly hit or miss as Dennis, and thankfully, he was a hit here in this episode acting like a hero. We all ponder who Liz will end up with (if anyone) if this show ends, but I think Dennis is as good a guess as anyone. They have that perfect love-hate element that makes it work.