It was interesting watching Fellowship again after seeing The Hobbit. I haven't watched it in awhile (and am only a casual fan), so it was kinda cool seeing all the little callbacks to the earlier story. From the original versions of the stone cave trolls to mentions of the dragon and the Misty Mountains and the flashback to Bilbo in the cave.
Of course now that the much younger Martin Freeman is playing Bilbo in the Hobbit movies, Gandalf's comment about Bilbo having "hardly aged a day" seems a bit odd. The implication is that clearly he hasn't aged much from the cave flashback, but I guess now we have to assume it's from a later date.
I was also surprised to see that Sting had been slightly redesigned from LOTR. Figured Jackson would have kept little things like that more consistent.