After raging himself into an explosive death after being reminded that The Master never played with him, the Air Conditioner gets repaired by the now-adult kid. It's enough to make him cry.
Immediately after his explosion, Kirby mutters that the air conditioner "was a jerk anyway"... then briefly glances at him, implying that he felt at least a little sorry for him, or at least understood how he must have felt.
The last thing he says before exploding is how he can't help if "the kid was too short to reach my dials!" Rob makes a moment to switch him on and bask in his cooling before leaving, giving the AC some much-needed closure.
After making it clear just how much the other appliances annoyed him and that he had a terrible phobia of water, Kirby leaps into the waterfall to save his friends.
Any time Toaster gives that big, wide grin. It gives you a sort of warm, toasty feeling inside.
The subtle chain of events which help the gang evolve from a bickering group into a family: it starts with Toaster deciding to be nicer to Blankie (after its tragic encounter with the narcissus flower), who then offers to be the group's tent for the night (after they spend the first nights sleeping separately). Then, when he gets sucked into the storm, Lampy risks his life to recharge the battery by using himself as a lightning rod, which the normally smarmy Radio, once his sworn enemy, gives him some sincere respect for. And finally, Kirby, the most curmudgeonly of them all, throws himself into the waterfall despite his fear of water to rescue them. That Everybody Laughs Ending was well-earned.
After the appliances escape from Elmo St. Peters' shop, they are overjoyed to be on the road again. They pause as they overlook the "City of Lights". Against all conceivable odds and through the most intense and breaking experiences that could have destroyed any semblance of friendship any group of friends could possibly have; they made it together.
Combined with some of the most joyous and heartwarmingly triumphant music this scene could have possibly ever had, Lampy's single line, his subsequent whoop for joy and Blanky's touching, silent moment as he takes out the Master's photo and hugs it seals the deal in terms of Tears of Joy.
Lampy: Wow. (The appliances go down the hill) Lampy: YEE-HOOO!
The appliances admiring Rob's graduation photo and saying how proud they are that the little boy who used to play with them grew up to be a hard-working, accomplished young man.
While the other appliances are all dedicated in their own right to find the Master, few are as devoted to finding him as Blanky. Near the end when the Master finds them in the dump Blanky is the first one he spots and what does he do? He snuggles him like he was a kid again. Given how much crap the gang had gone through at that point and how much emphasis has been placed on Blanky's love of the Master, it's not hard to imagine how Blanky must have felt at that point.
In the Polish dub of 'City of Lights', Lampy's line as they're going through the tunnel is "When darkness is all around, I'll beam light". It fit well with the scene and it's a sweet translation from the original line as well.
When the appliances saw the parts shop owner rip the cord off his blender, they quietly grabbed their own cords. While Blanky doesn't have one, he instead grabbed Radio's for him.
When the dumpster truck arrives to grab the garbage can full of the five main appliances and dump them there, only TV runs to the bedroom window and sees this happening with a frightened look on his face, at first. Then, when the truck prepares to leave, he makes a mental note of the name of the disposal, foreshadowing his attempt to get The Master down there.
It's subtle, but Rob is clearly looking forward to showing off his family's cabin to his girlfriend, and presumably wants this to be a romantic afternoon where he shares his personal childhood nostalgia with her. The way they lovingly hold hand while looking at it indicates that she's thinking of staying with this guy long enough for them to be able to have their own happy memories.
She even puts her arm around his shoulder when they leave when she sees how sad he is to leave it for good. Awwww....