Once-ler: So you want to know what happened to the trees? I didn't think anybody still cared!
Ted: Well, that's me! The guy who still cares!
The second time Ted goes to see the Once-ler, he accelerates his scooter using the left handle; in the rest of the movie, the accelerator is in the (usual) right-hand handle.
When Ted opens a drawer looking for a nail for the Once-ler, a Minion figurine (from Despicable Me) is shown in the drawer.