The 300th episode of Family Guy was full of drama. If you don't like spoilers, stop reading RIGHT NOW.
Brian and Stewie
Brian accompanies Stewie to Vermont after he "accidentally" (drunkenly) eats the majority of Rupert. They go to Vermont to spread the ashes of Rupert. While on their journey we learn a lot about Stewie, Brian, and their relationship. The biggest discovery was that Stewie's attachment stemmed from a deep-seated insecurity that Brian wouldn't always be around.
By the end of the episode, Brian had boughten Stewie a new Rupert which Stewie somehow immediately believed was the original toy back from the great beyond. "And in the world of stuffed animal spirits, can we say he's wrong?" Rich Appel, executive producer, posed to TVLine. "Stewie is really the one who gave Rupert life, so their bond is going to be the same. It'll be business, as usual, moving forward.
Fast and the Furious
We saw another recurring theme when the episode began with Stewie watching (and ranking) the Fast and Furious series. Afterwards, Stewie drove Rupert off into the cosmos alongside Paul Walker. Rich Appel explained that scene:
Cherry Chevapravatdumrong did a spectacular job writing this script, and Stewie is really just channeling her. She is obsessed with that series, and the ranking Stewie goes through … she will fight to the death defending it. We, of course, didn’t alter her ranking or her rationale. But that was among many of the things she brought to the episode, a sincere knowledge and love of that series.
Appel also said that this appearance was not meant to be viewed as a joke but rather a "genuine" tribute to the actor and the series.